MSNBC either didn't think anyone would catch them, (updated with outrage)

or didn't care; either way, they're a fine example of "You only need to know what we decide to tell you" journalism.

Update:
I ran across this at Ace, and it caused me to think a bit more about this. The above was when I first read of it, and it was kind of "So a Big Media 'new' broadcast screwed with footage and lied and changed the story. Ho hum."

After a bit more thought, it's become "These bastards claim to be reporters?!? They screwed with the video to present only what they wanted people to see and think, and used that to push a bullshit race-warfare template they want to sell? God DAMN these people!"

We've become so used to clowns like these at MSNBC screwing with the news that if a lot of us don't think about it a bit, we don't even get that worked up about it anymore; we've become used to it. And that's scary as hell.
"A man at a pro-health care reform rally...wore a semiautomatic assault rifle on his shoulder and a pistol on his hip....there are questions about whether this has racial overtones....white people showing up with guns." Brewer failed to mention the man she described was black.
This is flat disgusting. These people claim protection of the 1st Amendment to lie to us, and call us names and insult us when we call them on it. They tell us that anyone who opposes Obama on damn near anything is a racist 'because there's no other reason to'. Never mind actual policy disagreements and such, those don't count because they don't want them to.

Damn these sorry excuses for reporters for so screwing with the news that we've become used to it.