I just spent fifteen minutes typing feedback but when I pressed submit, I lost it all. So I'll give you a less in-depth response but if you want more opinions then reply again.
My two main points for you is to
a) make the two minifigs closer by:
They should be closer because as of now, the red guy leans seems to be reaching for the other person's face. That should explain Mighty Wanderer's reason for it to look weak. The swing is slow and that is because it took you too many frames for the arm to rotate all the way to make contact. Reducing the gap between them means you can take less frames and sell the illusion of speed. Powerful punches are up-close.
b) move the legs more. It gives more life to the minifig. Use Fancypants' video as a reference.
Youtubemy dad doesn't want me to brickfilm on because it's his computer, but he's not home right now at the moment. -FilmyGuy1