Alright. First of all, Ventrilo, like nachius said, is a voice chat program a lot of gamers use to communicate through mics and speakers/headphones. It's MUCH easier to coordinate tasks in such in games when you can just talk rather than type it all out. So people log on to a Vent server, hop in a channel, and start talking.
So in these videos, someone is coming into a guild's ventrilo server and intentionally trying to piss them off by playing extremely loud, annoying, and/or redundant audio clips.
Secondly, LMAO! The first video was kinda funny, but that bitch was retarded. It does not take that fucking long to find out who's doing that. But man, that second video had me dying, especially right at the end. "You guys should be in Vent more often..."..."Oh hell no"...."WHAT THE FU-BOOOOOOOOOOOOOOOOOOOOOOOOOOM!" I fucking lost it.
-Kevin