Yes! Go into Applications / Utilities, and fire up Console.
Under "System Log Queries," click on "ALL MESSAGES"
Now, as BEST as you can remember, try to figure out the exact time your video made your computer reboot, look through your Console for that time-frame, and voila -- the answer is in there! (Or, at least a clue)
My two-cent guess? Overheating. Something overheated. Either your GPU, or CPU, or something. Make sure you don't have dust blocking the fan intakes.
Have it checked out. Overheating = not good.