What type of mechanics should I look for when looking at a video of myself pitching?
Just video yourself and post them up. There are several very good members who will give you great feedback without being overly critical.
It is a good idea to post several pitches with views from the pitching arm side. Videos from behind the plate are also helpful. Make sure you are zoomed in enough so your image mostly fills the frame. It is hard to give good advice if you look like you are an ant on the side of a building.