Ok, I went to the Sacrificial Chamber in Vault 11 ... saw the movie and fought the robots. Now I am locked in the bloody room!! Where's the key to get out??

Check the vault mainframe. One of the messages unlocks the door (There's not an unlock command.)

Yep. Go to the left (from facing the lovely slide show) and into the room with the mainframe and select [Override Lockdown].
-Gunny out.

Thanks!