It is true that betas are allowed to have glitches. That doesn't make them any less entertaining to watch. And, hey, who can complain if Halo Reach still has bugs? What people are playing now is just a beta.
Up top is the best glitch I've been about to find on YouTube so far from the Halo Reach beta that's been running since early-access began late last week. We are seeing a player, their character shot dead, revived in their character's corpse. The dead body can't move, but it can fire a gun.
If, however, you're more of an unexploded-grenade glitch fan, you may prefer this:
Or do you like the old glitch stand-by of falling through a game world? Everyone loves that:
Wait, no? You're a fan if the Wingdings font? Then go to the 1:00 mark here for the Halo Reach glitch made for you:
I'm more of a dead-body-can-shoot glitch kind of guy, though, so I declare the top one as the best one.