First of all, you've got pretty good mechanics. I won't go into that as it is Brent's job.. He obviously knows the mechanics better than me. I do have a few things you need to look out for, pitching on the mound is completely different to flat ground. I struggle on the mound even though I pitch perfectly fine on flat ground. Maybe it's because I never really pitch on the mound so the muscle memory isn't there. Second thing is that throw a ball. Even if you have to hold it, it's better than not throwing or holding one at all. Throwing a baseball puts stress on the muscles which may change the mechanics. Other than that, focus on speeding up your mechanics. To me it looks like you are moving slowly to get the components right. Well, couldn't you use a camera? You don't have to use the computer to film yourself, even if it's a bad quality one. If you don't have anyone to film for you just put the camera on a table or the ground where it can see you and you should be fine. X)