Hello.
I'm the author.
Now, at last, I explain the motion tracing.
It differed from the explanation of the basic operation.
The tracing ways vary from person to person.
I am not very good at tracing motion.
But, I will explain the basic tracing guidance sketchily for the people who could make nothing of the motion tracing.
First, you prepare the tracing target video.
The movie file format which MMD can load is only avi.
But, it is the first barrier for the beginners.
MMD can not load the movie file or reports an error even though it is an avi file.
Why can't MMD load it?
You may find the answer by googling the "codec".
MMD can not load the movie file even though it is a avi file indubitably.
Maybe, that's because your PC doesn't have the files needed to load it.
By the way, when you encode a video to avi, the fps MUST BE 30.
Sometimes, fps is 29.97 or something.
But, please make fps 30 definitely.
So, maybe, you can not use the downloaded movie file directly.
Please make the fps 30 movie file with the encode tool.
If you don't do it, the motion timing will be off when you made it partally.
And you will want to die a little.
Please be careful.
Now, it's how to select the target movie.
I understand that you want to select the music videos or the strenuous dance videos.
But, the easy video for tracing dance motion fulfills these 2 terms.
The idol music videos or something has a lot of bust shots to show the face.
When the camera is bust shot, you can not know the motion of the legs at all.
That's why that many tracers select the fanmade dance videos, not the commercial music videos.
But for the time being, you want to make something as exercise,it's the best way that you select the video you love.
The most important thing for tracing the motion is keeping up your motivation.
You should select your favorite dance.
Even if that is a thorny path.
Now, have you prepared the video?
The high image quality is better.
But, there is a possibility that high quality video slows MMD processing.
Please be careful.
You select the "background" -> "show backgrond AVI file" at the menu bar and load the video file.
And you load the music file if you have it.
You select the "file" -> "load WAV file" at the menubar.
Then, you load the model which helps your tracing.
When you use the barely-clothed model, in other words, the model without unnecessary cloth, you will trace it correctly.
When you use the long long skirt model or the long coat one, it's hard to know that the legs are not good under the skirt.
But for the time being, I guess that you should use your favorite model.
When you make the model smile, the model will motivate you. 
This is called the "The Pleasant Miku".
Now, I give kindly explanation to super beginners before working.
Please pay attention to the maroon "model manipulation" panel.
The screen appearing when you select the "camera/light/accessory" is for making the camere, the light.
You can not move the model bones at this screen.
After loading the model, the model name is in the list.
And a screen which you can manipulate the bones and the facial expressions at appears.
At the model screen, you manipulate the bones and the facial expressions .
At the "camera/light/accessory" screen, you load the stages and the accessories and manipulate the camera and the effect .
Even if you can not find the bones, please don't panic.
Now first, you make the first dance pose.
The black table or something is the "frame manipulation" panel.
The "frame" means one picture.
The green line at the "frame manipulation" panel means displayed frame at the MMD screen now.
When you push the "" buttons at the upper of the "frame manipulation" panel or use the left/right arrow keys on a keyboard, the frames change one frame at a time.
You know that the green line is moving .
She starts dancing from this point in this video.
Let's select the frame and register this pose with this frame.
It is said that the bone manipulation should start off with the bone which is close to the center of the model body.
The first is the center bone.
She doesn't crouch, doesn't reach up, doesn't sway toward left or right at this pose. 
So, you leave it alone for now.
The next is the lower body or the upper body or the leg IK.
I offten move the leg IK first in these bones.
You put the left leg IK bone forward temporarily with the movement icon in the lower right portion of the screen.
You push the Enter key and register the key frame.
You pull the right leg IK bone back.
You rotate the model and check it.
She stands on tiptoe.
It's how to stand on tiptoe easily.
First, you select the leg IK bone.
And while holding down the Shift key, you select the toe IK bone.
Then, the leg IK bone and the toe IK bone are selected at the same time.
And, the toe IK bone is movable and rotatable.
So, you rotate the toe IK bone...
Look! You can lift the heel easily as the toe is grounded.
The leg IK bone positions are fixed.
You were supposed to make a correct pose.
But, you are uncomfortable about this pose for some reason.
When you rotate the model and look at the pose closer, you find that this pose is very unnatural.
Because the center of gravity is too far back.
For the time being, let's move the center IK bone forward with the movement Z icon.
That's almost right, isn't it?
Now, I guess the center of gravity is in natural position of upright figure.
But, something is still wrong.
Because the forward foot bottom is not grounded properly.
The very important point of making the leg pose is the "grounded feeling".
If there is no "grounded feeling", the motion will be fluffy motion, not down to earth.
What should you do?
Hmm... Now, you rotate the low body bone a little.
Then, the pose is beginning to steady down.
But, the direction of the toes are differ from the sample a little.
If you think so, let's rotate the leg bone or the knee bone.
The immovable leg bones and knee bones play an important role at times like this.
But, when you are beginner, you should not use them a lot immoderately.
Let's use them at pivotal points.
If you feel something is still wrong, you rotate the leg IK bone.
The leg IK bone can move. 
In addition, it can rotate.
You select the leg IK bone and display the rotation handle with shortcut X.
How about it?
You can do same thing with the toe IK bone.
But, I don't recommend it.
I guess that it's wise to keep your hands off the toe IK bone and the ankle bone.
If you touch them, you may be stuck with big trouble.
It except as making a ballet motion.
Let's set the direction of the leg with the leg IK bone.
The upper body slouches a little.
It's almost OK.
You push the Enter key.
When you move the bone, please push the Enter key properly.
Even if you intend to correct the pose later, it makes no sense without registering the key frame.
If you register the key frame, you can undo with the "undo" button as many times as you want if you make a mistake.
And you can delete the key frame, too.
Please form a habit of pushing the Enter key when you move the bones.
You check the whole.
And you lower the center IK bone a little.
At long last, he is becoming like a human.
Now, the next is the arm.
She lowers her shoulders.
So, you lower the shoulder and the arm.
You move the wrist like this.
OK! Good! Good!
You cheer yourself.
Now, let's make the left arm pose after making the right arm pose.
The pose is much the same with the right one.
Although, strictly speaking, it's different.
But, if you are not picky, let's copy.
You select the shoulder, the arm, the elbow, the wrist at the same time while holding down the Shift Key.
Of course, you can do the same thing with clicking the words at the "frame manipulation" panel.
And, you push the "copy" button at the "bone manipulation" panel and push the "revers" button.
Then, you can copy the bone movements as mirror-reversed ones.
But, the key frames are not registered at this time.
So, please register them properly.
Of course, you can select registered frame keys at the "frame manipulation" panel and copy and paste them as mirror-reversed ones.
In that way, you copy the registered keys.
So, you don't need to push the Enter key.
I guess this is about right.
You rotate the model and check it.
Hmm... I guess he should lift himself up.
So, you lift his chest.
The next is the head.
There are the neck bone and the head bone.
So, you wonder which should you use.
I guess that you should not move the neck bone widely.
When you move the neck bone widely and use the pose for another model, if the another model is different in head size or neck length, the pose can go broke like a monster.
Especially, big head and narrow shoulder model is mainstream for female models.
When you use a motion made with a female model on a male model, something often happens that you say "Ouch!" to.
So, please check the motion, correct it, and use it when you use a female motion on a male model.
Incidentally, the shoulder bone is the same.
A lot of female model shoulders are the same as nothing.
So, sometimes, a shoulder movement is too narrow or nothing.
When you use the motion on a male model, the male model will be unhappy depressed shoulder pose.
When you find it, please correct it before use it, too.
Additionally, a male model eyes size are smaller than female's ones basically.
When you use a facial expression data made with the cute big eyes miku model on a male model, sometimes, his eyes will roll back in his head.
When you find it, (omission)
It's nothing unusual that model arms get buried in a body or get uncoupled.
Sometimes, model arms touching a waist get uncoupled.
Sometimes, model hands making a heart get uncoupled.
Moreover, a female model mouth is small.
So, when you use a female facial expression data on a male model, his mouth is like this.
Especially, when "o" is big, it's troublesome.
Let's adjust it with the "frame" -> "multiply of facial expression" in the menu bar.(V7.30)
(V9.26: "edit" -> "multiply of facial expression")
Sometimes, I forget to correct them and panic.
Please correct at least them which are on camera.
I get back to talking about the neck bone.
Well, I recommend that you move the neck bone just a little.
You should move the head bone basically.
You tuck in his chin and push the Enter key.
That's almost right.
It's almost OK, isn't it?
If you think so, let's select all bones by pushing the "select all" button at the "bone manipulation" panel and push the Enter key.
Then, the all keys are lined.
And this pose, even the end of the finger, are fixed at this frame surely.
I explain the advantage of this method later.
Please delete the all parent bone key frame properly.
Next, you make the movement to next pose.
But, this video is over.
See you later. Good-bye!
