It's a lost cause. Our school sends home permission slips to allow the teachers to post pictures and videos of our kids on the school website at least once a year, sometimes more. I always say 'no' and my wife respects this, but she gets annoyed with me. She thinks I'm paranoid, and I told her I'm not paranoid, I'm just trying to make a point to the school, and in a way that's fairly painless for us.
Then one day she signed a permission for a video to be posted without consulting me. I was a bit upset, and she started saying that "it was password protected with a different password for each class." I got her to login to see our classes videos and pictures, and I could see at the top that once you were past the login page, it didn't seem like there was any session or anything. I showed her how I could take the URL for that picture and post it into another browser and it let me in without asking for a password. She still didn't quite get it or believe me. The URL was in the form of a GET request, with a picture ID number in the URL. I just started modifying the URL and typing in other numbers. Not every one was a hit, but I started bringing up pictures of kids in other classes. I said, "how can I see these if you've only entered the password for our daughter's class?" That finally seemed to prove my point, that the school (and whoever their web portal supplier was) just wasn't competent at making this secure, if I could get past their security in a few minutes. Unfortunately I can't really report that to the school or anything because I would just end up with police at my door.