That pretty much explains the weirdness. Michael Clayton and Juno missing Ensemble on their own wasn't likely.

No, Michael Clayton and Juno didn't have screener problems like Sweeney Todd, Atonement, & There Will Be Blood. So them missing Ensemble means the actors purposely chose to vote films like 3:10 to Yuma, American Gangster, and Hairspray over it. So if they couldn't make it over those films, there is no way they can make it over both those films and the unscreened films as well.

Go, Hairspray, Go!!!!!

You can never say "no way," especially with as many previous honors Michael Clayton and Juno have gotten. I personally think they will both be nominated.

Seriously, though, in the case of There Will Be Blood...screeners or not won't matter. It's not an ensemble film. It's a one-man-showcase something that most reviews explicitely emphasize.