This seems to be a recent and common problem for a lot of extensions and scripts that facilitate YT downloads... "Video Downloadhelper," "Easy YouTube Video Downloader," and this script all have similar issues. I've attached screenshots of the YT HTML5 player, as well as the "Easy YouTube Video Downloader" menu.
The only format that shows up in the menu is 360p. I suspect that some kind of change on YouTube's end (possibly related to the HTML5 switch) has taken effect within the past few days.
It might be helpful to note that even the YouTube HTML player itself will only show 360p as an option, unless you go into about:config and set `media.mediasource.enabled` to `true`.