Firstly, congratulations on a truly great video player. That, plus the fantastic support and the way you respond to suggestions, can only mean it will get better and better. I've bought and tried MANY video players. Some are lousy, some have a few good points but none come close to Infuse. What pleases me is that you have the basics right (being able to reliably and smoothly play many formats) and you are now nailing the rest of the useful features and bells and whistles.
My suggestion is of the bell and whistle variety which shows what a good product you have. I find I am often wanting to find a particular scene, song etc and so want to jump forwards and backwards a lot in a video. The scrubbing feature works nicely but you can't see where you are until you stop scrubbing. By that I mean it is not like a traditional forwards/backwards where you see the picture as you move. I use an iPad Air with good wifi and I find even with that, buffering takes a few seconds to settle when I play. Hence any movement forwards or backwards is a bit of a random thing - move, wait, check where you are and repeat until you find the scene.
[Later] I was puzzled as to why scrubbing was so called and I realised it's because it scrubs nicely when you play a local file. Most of my playing is from a nas across wifi where the buffering has a big impact on the usefulness of scrubbing as a way of finding a scene. I find the best way to find a scene when playing a remote file is to have an easy way to jump different intervals - say, 30 secs, 1 min, 2 mins. One player I used allowed you to configure the jump period in the settings. Another player used a one finger swipe to jump one interval and two fingers to jump a different interval. Is something like this possible? Or perhaps the interval could depend on how high up the screen you swipe, eg the higher on the screen the longer the interval.
You may already have lots of gestures planned for other features and I'm sure too many can get confusing but maybe that's where settings come in. EG to some, a swipe to change volume is important but not so much to me.