To get this working on a dream800 (black hole) as Smirnoff posted then you have to remove the existing one that comes with the image before installing the new one.
Smirnoff posted the working one and I've also added it to the downloads section for the dream800HD clone.
So, I'd maybe fire up DCC (dream box control centre) remove the existing one, reboot, then open DCC and then re-install it, re-boot and you should be good to go.
(If you haven't got dream box control centre, then you should get it, makes installing package files a breeze, and lots of other things as well, it's like an all in one program for the dream)
So yeah, in all the images that I've seen that come with "youtube" they never work, have to be removed for what ever reason and the enigma2-plugin-extensions-mytube_experimental-git2. installed.