We've been having the same problem with iframe errors when we use khan academy. On Feb 6, all embedded videos had this problem regardless of whether you were using youtube education or not. On various forums I read that people thought they changed a header value and it blew up the cross-domain iframe protection that exists in pretty much every browser. This was fixed the same day it broke but it seems like we have still had issues with youtube education users over the past month.
We get this error on most khan academy videos. I've seen no solutions for this, but I have a feeling most people are abandoning youtube edu filtering because it has had so many problems and has so many holes. For one thing, the iOS app doesn't honor education filtering at all. We may ditch it if we cant find a fix for this quickly.
