Basic video playback specifically is something we would like to see in the hopefully near future, and it's tracked on our backlog, although not with the highest priority right now. It's not part of the current RC for the next big update, but if there is demand for it, we can add it in for the next update (we are planning to be doing much more regular updates beginning with the next one).
With that being said, if/when we commit to it, it'll probably not go beyond simple linear video playback, probably with an audio output connection option. The use-case would be, as you also put it, editing audio against a video playback/preview (with or without audio from the video itself included), but not editing the video itself.
I'll add the rest to our backlog to think about, they sound like interesting and valuable ideas (pun inteded 🙂).