Coincidentally, just last week I was working on ochiba 2 again, specifically code to allow extensions to handle file types other than images (in my case, I was working on PDF uploads, specifically, which is nice because you can still generate a thumbnail from it). This requires quite a bit of change to how ochiba 1 works so I don't see it being available as a feature until ochiba 2 is done (no, I don't have a timeline for that!).
The youtube embed idea is kinda doable now- the custom parsing functionality should allow for you to take some post syntax like <youtube:abc123> and convert it into the embed code. I would imagine embedded video for other sites would work the same way.
It would be nice to have a thumbnail for the video appear as the posted file, then onclick it would show it in a lightbox, but I haven't figured out a way to structure the user interface for this. What would the user upload, if anything? How would the parser recognize this was a video embed? etc.