I can't top that incredible Confessor video Brian posted a few weeks back. But at least I can post something stupider. Madness Reign (top left) is definitely the dumbest thing I've seen in a while and the finest example of bedroom metalhead parody I've heard. From muttered "sound effects" and cheesy graphics to pointless chugging guitar and malinformed vocals, Madness Reign is like the road trip that Bruce Dickinson, Weird Al and Jandek took together last spring break. I'm also a fan of this guy's dadaist stand up comedy bits - below is a sample. I'd strongly recommend checking out the webpage - he's got 14 (!) albums out and a ton of music videos, all in the same vein and pretty hilarious. Top right is Axemaster's "Slave To The Blade." No explanation necessary.
I mentioned this Dum Dum Bullet (bottom left) video before, but it's really hit me how awesome it is. The guitarist is totally great, they've actually got a pretty unique sound and the singer keeps on showing up in different guises throughout the video! The song title is "Hey Mum, Who's The Junk?" Who indeed! Purgatory (bottom right) is the sort of band that makes me wish I owned a car, just so I could blast this shit while driving over the speed limit. Heavy midtempo thrash via Slayer with Iron Maideney fist pumping action. Add a healthy amount of progressive time changes, a bit of falsetto vocals, occasional shredding guitar solo-age and you're JUST under the level of smartness required to be ACTUALLY good. But this was only the beginning of a bright future: vocalist Jeff Hatrix went on to sing for seminal nu-metal giants Mushroomhead. Now that's smarts.