Yeah, that drum solo video of him was really cool. Definitely a bit too long but pretty awesome that it was done in one improvised take. Kinda hard to cover that much ground without running and missing a drum or two any shorter. Love the duct tape on all the drums and the crazy characters throughout the video. Big kit is definitely the highlight though, that's for sure.
His Dance of Eternity video is pretty badass actually as is his Metropolis and Liquid Tension covers. He was in Blotted Science and Behold the Arctopus and played with Jordan but I guess was too young and not popular enough to get the call for the Dream Theater audition. Makes sense, Portnoy is a gigantic Drum Hero and needs to be replaced by one.
Regardless, I personally can't wait to hear Mangini on the next DT album when he's actually allowed to write his own drum parts from start to finish rather than learning Petrucci's drum programming and just throwing in a couple different fills and flavor. Portnoy was great and all and his feel and energy is missed, but man is Dream Theater now officially the most technical group of musicians out there that normal people have actually heard of. Totally brilliant now.