There's a live stream going on here: http://www.comedycentral.com/dcrallylive/ Viewable outside the US too. So far it's been a comedic sketch of the political situation in the US. If you have any inkling of how the US political system works and you aren't an extremist then you will probably find this at least a bit entertaining.
Wyatt Cenac and Jason Jones just got done making fun of media coverage of the past few rallies on the National Mall. Jon Stewart's opening lines were making fun of all the arguing over rally sizes of the Beck rally and the last Democratic rally at the mall.
Right now medals are being presented to reasonable people and to people who keep fear alive. The sarcasm and things extrapolated to the extreme is still thick. Even though it's more of the same this is absolutely hilarious.
These two performers (the white guy and the big black woman) were just on the Daily Show a couple weeks ago singing this same song. I was in the bathroom when Crazy Train was being sung, but it didn't sound like Ozzy. It was done before I got out so I didn't get to see it. Either it wasn't Ozzy, or he's really not as good as he used to be.
If I followed it correctly, over the past month or two.... it's not geared towards any particular political view, but is just a charity event to raise money for the National Mall. Obviously since Stewart and Colbert are hosting the event, there is the satirical swing on all political happenings, etc. as their shows usually have.