The video in the link has been changed since it was posted. The original video was unedited cell phone footage. Later, the video you saw, was an edited news report that included dash cam footage and cell phone footage, and commentary, mixed.
In the dashcam footage, he does say that line, although it is not the first thing he says as he takes off his jacket. The first thing is "I ain't got nothing." Then, after the jacket is off, he utters the line above, which prompts the cop to attack.
It is unclear what happened before he took off his jacket. Did the officer ask if the man had a weapon? Or possibly did he even ask the man to remove the jacket? I couldn't tell.
The added footage does make me very slightly more sympathetic to the officer, and who knows, perhaps even more information will come out that makes the attack justified. We'll see. That's what investigations are for. Still, I don't think it is looking good for the cop. It still seems like the best case scenario for the cop is the "If you don't do exactly what I demand the moment I demand it, I have the right to beat the hell out of you" defense.
It's a tough sell.
These videos always look bad for the cop at first, that's why people post them. Some turn out to be as bad as they look, others not. But once it's posted and deemed "an outrage" it is hard for people to admit they were wrong if/when new evidence comes out that supports the officer.
When I see such a video here, I know that the person posting it usually wants it to be the cops fault.