Yeah, it's doubtful this is a bug. Similar things like this have happened in Melee, but never to the extreme hilarity that is presented in this video. Most of the time in SSBM when a character was meteor'd flat into a surface from the air, the character would basically just hit the surface, and the momentum would basically be nullified at the expense of extended stun. A missed tech wouldn't necessarily cause this, although I have had momentum carry me after a successful tech. It's probably just a combination of SDI, paired with the new physics system that overlays the brawl physics that's causing the nonsense. I don't think it's game breaking in any sense of the phrase, but it is certainly interesting to see. It's only happened to me once during a game, and I never really bothered to question it.
Nice job getting a video of this though. It's not exactly a common occurrence, at least not from my personal standpoint, and I don't believe anyone I know personally who plays this game has experienced this firsthand, however it's still very interesting to watch.