You remove their face and change their voice in the video. At least, when you're talking about body cam footage. You also blur license plates, addresses, etc. That's what is already being done for information requests to law enforcement.

This isn't a hypothetical btw. This is actually how it happens in many jurisdictions, and some law enforcement agencies are being proactive about this and thinking through how to be more transparent without risking privacy of innocent or guilty parties (both deserve privacy).

Usually via the general fund of the locality where the video was recorded.