It's the old cliche of showing barrels in first person shooters. Sometimes the barrels have no real world reason to be there in a level. They are just around for you to take a gun and shoot it, causing a big explosion that you hope will take out some enemies.

So how about an environment that is filled with barrels? Lots of barrels? Barrels that are just waiting for, say, a Redeemer fired by a player in Unreal Tournament 2004 to start the biggest chain reaction of explosions we can remember seeing in a YouTube video? There's no need to wonder about those questions. Just check out the video above for the answer. Oh, and check this post on the BeyondUnreal message boards for some info on how the video was made (here's a hint: the video isn't rendered in real time).