Whether or not you “feel” safe has little to do with the actual security risks though, right?
Also, the TSA policy is to allow people to film interactions with agents (accountability when being publicly patted down/searched. But you can see how the definition of “interfering and revealing sensitive information” might depend on what’s being filmed. Bad guys who want to exploit any weaknesses in the system would be very interested to see hi-def photo/video that might help them determine what the system is capable of, how sensitive it is, or how it might be circumvented.
It’s not only photo and video they might be concerned about. Try standing around and just watching people come though a security check. They’ll come ask you to move along. Patterns, schedules, (agents rotating through various stations in the checkpoint) and protocols (how uniformly procedures are enforced) could all be used to help someone thwart security measures.