Also, in your timeline you forget to mention that prior to sitting on the guys prosthetic legs (the horror!) the guy got off two kicks. You then immediately say “oh my god! Oh my god! What are you doing” and you comment on them sitting on his legs. Did you not just see the fact that when he got off the guys legs the guy kicked him twice. prompting him to then sit on his legs.
If you are going to wonder at why a cop might sit on someones legs legs, and if you have video can you at least make note of the fact that he kicked the officer? WE can see the video, you know. WE can see that you seem oblivious to this fact. Are you surprised that a person who resists arrest, or resists detaining might have cops hold him down? Is this a surprise to you?