I never looked up the others, but they probably are real and still around. They're pretty common-sounding names, so they probably would have been snapped up a long time ago. I just checked Crusher, and yep, it's real. So is Bumpy (albeit, unused). Along with all the other gamertags on Dark Master's team in the ad: Siberias (again, unused), Buffalo Soldier, Pochi X (unused), Steel Crumpets, Sleeping Giant, and the AFC Captain Carnage.
wow, i didnt realize that this 'Dark Master' gamertag was actually real... i wonder if 'Crusher' or any of the other tags like 'Cheese Filter' they show in the video are real too? they look cheesy but they are like the de-facto gamertags
I've just remembered what I didn't like about the ad: that those two games (Chrono Warriors & World Cup Warriors) never existed.