alt Hacker NewsAgain I can speak only for Illinois (and 'chaps is more authoritative than I am) but for the most part you're not going to be axiomatically deriving what you can do with FOIA; most permutations of what can be done have already been attempted, and there's really rich case law. It's super easy to FOIA things! Lots of relatively normie people use FOIA. So FOIA lawyers have seen some shit.
Generally I'd predict that it's unlikely that you'll be able to do anything with a FOIA law to compel a vendor to do anything directly.
The real one is people coming up with minor, but recognized, reasons to request footage from different cameras.
Most everything is covered, as you mentioned. But there's a huge difference between things like Obama's birth cert(canned reply after paying the fee), and the entire US populations worth of people requesting a single 5min segment from a camera... But everybody wants a different camera, date, and time.
I suspect an organized campaign will sink the cities/flock, or they'll make the streams public and not retain anything. Public streams with no retention is how TXDOT handled this.