Actually it becomes easier...

Seems I got the UA version disappearing mixed up with the About box hiding of the version number.

For my UA, it seems adding uzbl beside X11 for a Firefox UA still works. Still, I'd like if there were a standard way of doing it for statistical collection purposes.

The impetus behind the video and audio feature disabling is that I don't like websites playing media without consent (e.g., it'd damn near impossible to queue up youtube webpages because they all auto-play). Plus, I have tools to download them and watch them in MPlayer where I get keyboard shortcuts, good seeking, and replay-a-week-later-with-no-download. It also allows me to drop gstreamer dependencies. The database blocking is mostly to hamper tracking and geolocation because I don't need my browser to know.

So yes, I realize that the train has left the station on these features being out there, but it doesn't mean that I'm going to allow sites I visit to control my computer without consent. It's silly that websites can play media without asking "Are you already listening to music? On a call? Listening to an audiobook? Watching another video?" and do nothing if so. If/when uzbl exposes the flags for black/whitelisting these things, I'll enable them again in my builds.