You are not the thought police. It's not for you to determine what other people can post on their private accounts. It is between them and the posting service. What I would put in my handbook is something akin to:
The band does not authorize or approve of any posting or publication of audio or video recordings of the band, its members, or any of its component groups, outside of officially approved (Insert name) ISD releases. (X School Name) band, its directors, (X name of school) and (X name) ISD are indemnified and held harmless from any legal consequences for the private social media postings of any private citizens who post any media of the (NAME OF) Band.
There's probably a much better way to word this - I'm tired. Check your district electronic approval form - it probably contains this language.
--Previous Message-- : Hello. I'm looking at making some additions : to our handbook regarding students/parents : posting audio/video on social media and : would like to request examples from any of : you who have already addressed this in your : policies. Thanks. :