As a one-time snare drummer for a Fife & Drum Corps, let me just say these guys have some serious chops. It's necessarily what they're playing is incredibly difficult, but rather that it's incredibly precise- you can hear every individual stroke even during rolls and ruffs.
Of course, this shouldn't be surprising, considering they've been invited to perform at the prestigious Edinburgh Tattoo multiple times.
As an interesting aside, while looking up a little information about the Top Secret Drum Corps from Basel, Switzerland, I found this little tidbit:
"During the 2005 Fasnacht [a Basel Festival], Top Secret made local headlines with a prank meant to poke fun at the stringent rules of the Basel carnival. At issue was a policy which forbids foreigners from marching in the Morgestraich. Top Secret circulated news that it had invited a band from Oman to march at the event. The "Oman band" then appeared in costume at a press conference where angry carnival bolsters expressed their outrage. When the "Oman band" revealed itself as Top Secret members and friends in disguise, many Fasnacht participants and organizers were not amused whereas a majority of the public found the gag hilarious."