Your casting is good, and you have an excellent foundation to work from. Many of the guys here have already talked about some of the things that will help you cast better, i.e. stopping earlier on the forward stroke, smoother acceleration both backward and forwards, etc.
Here are the most important elements for a good 2 hand overhead cast…
1 - *Most important* You must draw a strait line with your rod tip both forward and backward. You can use different planes (drift to a different plane between strokes), but the actual strokes must be strait.
2 - Drifting upward and back a little after you have finished your back stroke.
3 - Accelerating smoothly both forward and backwards.
4 - An abrupt but smooth stop at a high position on the forward stroke, or just ever so slightly lower then the plane of your forward stroke.
5 - Use mostly your upper hand and less bottom hand. The bottom hand is used mostly just at the very end of your forward stroke. This accelerates the rod tip just enough at the very end of the forward stroke to initiate some energy into the line (kind of like the double haul does with a single hand).
6 - The bottom hand should follow the top hand during the back stroke. Try to avoid having the bottom hand drift or push away from your body during the back stroke. This will cause the rod tip to deflect and you’ll loose the most important part of a good cast, a strait line. Watch your backcast. Is your line traveling behind your body? If it is, then your backcast is swinging around behind you and you’ll loose a lot of power.
There are a few other things that’ll help, but I have a tyung class starting and have to go. I attached a couple of videos for you to view.
Tight Lines Fly Shop