I have read many places that taking pictures in public, of people in public, without permission is legal. For the most part if the person has no "reasonable" expectation of privacy, you can take their picture (in the U.S.A). I have heard that film is a little more complicated, so I wanted to get an opinion on this from people who may have experience in this area.
If you are going to film a scene inside a restaurant for instance, and you have the permission of the owner to do so, could you also film your subjects entering the restaurant from the street without getting permission from other businesses around it and the people who may be walking on the street? This would be a non-profit project for publication on the web.
Would it be necessary to get a permit for this type of filming? Or would it be legal since they don't have a reasonable expectation of privacy?