Pymongo's documentation is generally inconsistent, they've currently got three different explanations out there on Binary fields, none of which are actually up to date. I've had these cursors work fine as iterables, but I've also had them break on StopIterations for reasons I was unable to pinpoint. As far as I could tell it has something to do with pymongo handling keyword searches differently (like $regex) and it was generally brittle enough for me to feel uncomfortable using it as a normal generator.