It's usually best not to watch surgeries before you have one. For a TKR, yes, they move the leg aggressively before they close to make sure the prostheses are properly set. It looks harsh but it does not do any damage. I have never heard anyone complaining of sciatica after a TKR. I suppose it's possible, but rare.

Again if you're planning on having a TKR and get queasy at surgery videos, don't watch!