I presume he would have turned his cruiser's dash-cam off at this time, since by his own admission filming was illegal.
Avi Adelman is bit of neigborhood gadfly in the Dallas area. He films a lot of police action and other things in his neighborhood. Recently in Dallas a TABC office tried to block his filming of an arrest by shining a flashlight at the camera. Defense was the person arrested did not want to be filmed. He filed a complaint, no word on the result.
http://www.barkingdogs.org/news/node/419