Nope, not gonna happen (if you don't want your girlfriend/wife/roommate(s)/friends to know you're watching porn, just don't install). But the source is open, so if anyone wants to add features they're missing, please do 
No worries.

I don't have any issue with the gf. More visitors - friends, family, children (nephews, nieces, neighbours) who might be round to watch a film or a bit of TV (my Mac Mini with Plex is setup in the living room). With it being called 4tube, it sits first in my list of video sources - not exactly discreet. I could change the ordering, but I do like them alphabetical.
Unfortunately I don't have the skills or the time to gain the skills to add the functionality, so I'll pass, but kudos on a superbly functional plugin.
To be honest with a gf and the pornhub plugin I have enough! 4tube would have been a nice bit of variety.