Thanks for the suggestions. Still figuring out the best way to handle thumbnail generation and loading. It's an intensive process, which could cause performance issues when running in the background. Best way might be allowing users to supply their own thumbnails with a png or jpg file. I like the idea of putting these thumbnails in a ".thumbnails" folder instead of the same folder as the video.
In regard to allowing key presses to act like the menu is hidden when the cursor is outside of the menu, I'll see if I can get that to work. It might cause issues with other input methods.