I was under the impression that recording in a public place (on the street) was legal. The camera was already running when he was stopped, and the recording of the cop was incidental to the rest of the recording. I doubt the cop would have tolerated a "wait a sec, officer, I'm recording, is that OK?" from the biker.
The DA is overreaching. However, the guy probably should not have posted the vid to youtube, but instead given it to his lawyer.
Anyone in the SE region want to invite him to a trackday?