September 13th marks the release of the complete season 4 of "Big Bang Theory" on DVD and Blu-ray in the US and Canada. The nerd-centric show has amassed a fervent audience that will be sure to be snapping these up for posterity.

The set will include all 24 episodes as well as four bonus features:

• 'Actor on Actor: The Big Bang's Theory of Relativity Featurette,' (The cast interviewing each other.)

• The Barenaked Ladies on Big Bang Theory Featurette' (The band behind the themesong interviews and music video shoot.)

• 'The History of Everything' (The Aforementioned music video)

• Gag reel

 

Take a look a the clip embedded above. It's probably from the first featurette, "Actor on Actor" but it could easily be from the gag reel, as it's very very silly.

It features series stars Johnny Galecki and Kaley Cuoco asking each other questions from note cards, but it may be late in the day as they appear to be a little punchy. Things get silly, then weird, then they just give up. It's a great glimpse at the chemistry the ensemble cast has with each other both on and off screen.

"The Big Bang Theory" complete season 4 goes on sale September 13th.