SMTube is in Debian main (as of Jessie), but Parabola finds it non-free and
it seems like Trisquel does too. I trust their judgment over Debian's so I
have stopped using it.
I just tried gtk-youtube-viewer in Flidas and it does almost everything you
describe in your initial post. The only thing missing is the ability to click
on a YouTube link in-browser and have it open in the player.
I think that this Firefox add-on is intended to achieve that. The license is
not GPL-compatible but it is libre. However, I could not get it to work with
youtube-viewer. It seems like it was primarily intended for you with
Minitube.
I also tried to get Minitube working in Flidas. Unfortunately the version in
the repository does not work. You get an error about missing Google API key.
It looks like Minitube has to be built with such a key. You can't get a key
from Google unless you have a Google account and enable non-free JS. The key
also presumably identifies you to Google each time you watch a video. There's
a deb file available from the official site. I was unable to test it in
Flidas because it's only available in 64-bit and I'm running Flidas on a
32-bit machine. However, I assume it was compiled with the developer's key.
If so it should work, and while YouTube can probably tell that you are using
Minitube it won't necessarily be able to tell you apart from other Minitube
users.
