As an active Action! user and supporter, I'd like to emphasize on the already mentioned webcam problem, it's a shame not being able to move it wherever I want; as a CS:GO player and youtuber, I'd be covering up important information in every corner of the screen. So letting us move it freely would be great. Even better if we could get two separate tracks on the video recording, one for the webcam and one for the video itself, so we could resize and move freely the webcam after we finish recording. Just a couple of thoughts here and there.
Also, as people already mentioned, a pre-record feature would be great too, but not mandatory as much as the webcam issue. Also more flexibility for livestreamers would be great (even though I don't livestream), I'd rather use OBS to stream, for the time being.
But the most important thing of all is... Letting us choose which applications' sounds to record and which to discard. That would solve all my problems, really.
Good luck mirillis, your program would probably be god tier after that. It would be the staple of every youtuber. It's already in the top tier I'd say, but with that, hey. There would be no competition