There are literally thousands of possible radio channels on which you'll find this kind of activity. If you know the name of a production film company, or a TV production facility then you could look them up on the FCC database and find out where their operating frequencies are. Same goes for a TV station. Start at Home | FCC.gov and look for various prompts, and also use the database that's part of this Board. Some companies, rather than use frequencies assigned to them, will rent radios from a rental company and use frequencies licensed to the rental outfit. It's also possible for these outfits to use wired intercom systems which have no radio component, but then again some intercom systems do use radio as part of their operations. It can be a complicated subject but if you dig into it you'll find a lot to listen to.