Let’s face it as useful as YouTube is showing techniques, it is less than being there. It is more useful if you already have something like the technique being shown, but as movements are over in a blink of time, many times you are not sure what happened.
I have worked up an answer. It is not perfect, and it is time consuming. But with patience I think it is useful.
1. Take the YouTube video you want to use and put it on hold,
2. Then slowly move the cursor forward showing each technique, at best one fraction of a movement at a time. (this can be the tricky part as it is not easy to move so accurately. But patience over and over does yield the answer.
3. Using Control- Alt- Screen Print, make a screen capture of the movement wanted.
4. Then using Paint copy the screen print into a picture you can save, and do so.
5. This will take as many screen captures and screen prints as needed.
6.Then go to Windows Explorer and go to the location you saved the photos of the screen prints.
7 For each YouTube Screen Print, then Open with Microsoft Picture Manager.
8. Then when the screen print opens, Selece Edit Picture amd Crop. And move the crop bars to cut out all the screen but the photo you want to save.
9. When finished select the Done button and the larger saved photo should appear.
10. Then choose to Save the photo (if you do not do this it will revert to the original)
Yes this is a discipline and a lot of work.
But you then have detailed photos of the movements.
Copy them into a ,PDF file. See them as individual photos sequentially presented. If you page through the file faster you can grasp the flow easier than on YouTube.
This is a tool, it is not a fun process, but it is worth it.
Example: 宮里信光師範（剛柔流直心館） 四向鎮（シソウチン）分解--ムチミ--
Technology of Nobumitsu Miyazato Normal (Tsuyoshiyawara flow Hitagokoro Museum) flow soften the butt 'of' and 'viscosity'
These are photos of one of the techniques.
Work hard, work harder, Think of the results. They will make the effort worthwhile.