Viral Video Of The Day?

So says this news story. But I'm not sure why the comments on youtube and the news story have so much outrage.

But it's a pretty good law school criminal law question (and I'm making some factual assumptions) : Can a cop enter the home of a third person without a warrant to arrest a person for committing a Class C offense (disorderly conduct) when the cop didn't witness the offense?  In Texas, I believe the answer is no. (But it could be argued that the offense of evading detention occurred if the guy opened the door to the cop and the cop asked him to step outside to discuss the incident. I'd like to know what happened before the filming began.)