For you people who have the FFDShow codec installed on their computers, you may want to go into the FFDShow configurator and add FalloutNV.exe to the "Don't use FFDShow in" program list.

Oblivion.exe and Fallout3.exe are already in there.

Edit: Don't forget to do the same thing with the FFDShow Audio codec as well. I added FalloutNV.exe to that and it completely fixed the crash when opening the game launcher.

What kind of bug/conflict was there with FFDShow?

I think the game engine wants to use the codec for some media playback and fails spectacularly.
I noticed the FFDShow icon in the system tray after a FalloutNV crash and just remembered the old Oblivion/FO3 bug.