It really depends on the cops at the scene. If they aren't being interfered with, they will just ignore it. If you're a cop, you don't mind having your picture taken. It happens a thousand times a day. Everyone has a camera and every public street, shopping mall, and store has CCTV cameras everywhere. Most people never realize how many times a day they are being photographed.
Sometimes, the cops on a job are just too damn busy to deal with other people, even if they are interfering to some degree. To arrest someone for hindering requires that you disengage from what you're doing, explain to the idiot who is hindering what they are doing, give them an opportunity to stop and, when they don't, arrest and baby sit them before going back to your original job.
It's frequently not worth the effort.