Priority 1 (highest)

Priority 2
Use ffmpeg to convert unsuitable video files (how do we check this?).
Add keyboard command for "top menu" in preview mode.
Add support for videos in preview mode.
Support more than 99 videos somehow (grouping them into titlesets won't help)
Allow explicit ordering of videos.

Priority 3 (lowest)
Provide a means to specify menu & audio language.
May need to override default menu navigation actions because dvdauthor seems to cause rather undesirable behaviour when buttons are not arranged in a grid.
For any page with no links, add a "back" link (this raises the issue of localisation, of course).
If a page is too large, split it and add "next" and "previous" links (seems very difficult).
Set Mozilla's idea of the pixel aspect ratio to match video pixels. (For extra credit, scale preview mode to correct for the differing aspect ratio.) This seems to be impossible.
Avoid running Xvfb if we're only going to display an error message.
