Generally the laws on video recording are based on where the camera operator is standing while filming. If you have a lawful right to be where you are, it's probably ok to make a video. But take a look at the facts in Shulman v. Group W Production, Inc. (1998) 18 Cal. 4th 200, where the camera crew was lawfully present but intruded on a private encounter. Very much depends on context, at least in California.