If I'm not mistaken, inline images (or at least captions, which would be really easy) is already on the drawing board...
I, for one, wouldn't want to host videos AT ALL, tho - first, you'd have people uploading 5-100MB video files which you'd then have to automatically convert to Flash. Why reinvent the wheel when other sites host videos already? Let THOSE sites eat up their disk space and bandwidth - not me!
