You don't need people to sign a release form if you're a photojournalist or anything considered to be an editorial source.
But as professional filmmakers know, you absolutely do need a release form if you're producing anything commercial (for sale). Or if you're pushing the boundaries of this like they do when filming Law & Order, to at least put up prominent signs so Manhattan pedestrians know they might wind up on the show if they walk down a particular patch of sidewalk that day.
Isn't there a strong argument to be made that posting on social media without consent is therefore illegal? Because while you're not explicitly selling the video, you and/or the site is monetizing it via ads, which these days is the same thing.
Has this been tested in court?