xhonzi said:

The "ending" video was pretty clunky. I don't think it was any different for having the DLC installed...

If the DLC isn't installed, the game ends with you dying in the chamber. Unless you made the Brotherhood of Steel girl go in there to take care of it for you.

If you have the Broken Steel DLC installed, then as you saw, they retcon the ending and have you wake up from a coma. If you beat the game without any DLC installed the first time like I did, then once you install Broken Steel you have to load a save right before the end of the game (which I had), or play back up to that point to access the DLC which automatically starts right after the ending.