All of them, but this one most since I love seeing the cast interact.

Probably the gag real and Cast on Cast interview. I was kinda hoping for better bonus features but these sound okay too. I wish they'd put a bonus DVD Easter Egg you have to find, I love those.

Most definitely !

I wish they'd do cast/writer commentary on episodes, like they do for HIMYM and like they did for Friends. That's my dream bonus feature.

Yes commentary would be amazing! I wonder why they don't do that actually? I love commentaries, you usually learn interesting things and the casts crazy offscreen antics XD.

I know, right?

Commentary would be great!

LMAO "Actor on Actor" XD

Haha! And now I want to claw my eyes out because Mayim had tweeted that she and Jim are interviewing each other, and I do not not not want to see that kind of "actor on actor".

Actually I would love any of these, I chose the interview one because it would be nice to see like who is maybe the funniest off the set, or other details that we might not know.

Secretly I would love the music video thing too, if they did it like The Rembrandts did with "I'll Be There For You" where they had the cast in the actual video and they were playing around with the instruments as such haha, I can imagine Wolowitz on the drums and Leonard jamming on the guitar.

Definitely the music video!