Today I use VLC player to watch my videos. It is kind to show all the file formats I use and has the basic functions supporting my learning. I use mostly the arrows on the left/right to watch slow motion or the rapid version.
If I need to repeat many times a section I mark the start and end points and let the player repeat the interesting section as long time as needed. When the repetition is going on I can change the speed with arrows on left/right or in playback speed box. There I can also change the speed with small adjustments.
But be careful to watch the videos only in slow motion - my brain adapted very soon to the new speed and I lost the effect of clear observation.
Today I use a lot of rapid motion too! It keeps me busy and alert. My brain learns to keep track of the fast movements and get used to the new *normal speed*. When watching a normal one again the feeling is unstressed and comfortable!
It is also easier to understand and follow the dynamics within a whole dance when the speed is 1,5 or 2 times faster to normal.
You find here a short video of obtions mentioned.
DoubleArrows: Make it slower 67%, 50% or make it faster
Red dot: two clicks - a small film is created
Camera: one click - a picture is taken (using a lot of this option)
Repetition: hit the left to start, wait and hit the right one. When both are red repeating goes on and on and on.