I guess we're lucky here. The school and city bus drivers are pretty courteous. Heck, I pass the district school bus barn on most of my rural route rides and wave to the drivers. It's a popular route for cyclists so maybe the school bus drivers and cyclists are just accustomed to each other.
I run video on most rides. Boring stuff so I usually delete 'em as soon as I'm home. But if I encountered a genuinely reckless or aggressive bus driver -- not just an inadvertent brain fart -- I'd report it and send a short video clip. So far I've done that once in two years, a Domino's pizza driver who buzzed and nearly clipped me on a left hand turn where there was no competing traffic.
The brain fart stuff I just ignore. Everyone has an occasional bad moment -- including me when cycling. A week or so ago I didn't even notice the yield sign facing me while approaching a roundabout. I'd ridden through that roundabout dozens of times without encountering another vehicle. I was on autopilot and didn't yield to a driver who actually had right of way. Fortunately my vague hand gesture could have been interpreted as a wave rather than something rude. If they'd stopped I could have claimed I was bashing myself in the head for being an idiot.