When I had live video shot in the past, we hung large, dated signs up that clearly declared our ownership of the video. The signs also strongly suggested that anyone that did not want to be included in the video should please leave. We also had our camera crew shoot the signs right into the footage as ‘evidence’ if needed.
Here’s a video and photo release (below) you can use when you believe it really matters. Get an attorney to check this for you. Always try to get verified (check an ID) addresses and phone numbers on these releases.