Not trying to put you on the spot, but do you have some examples. I'm having a hard time thinking of "great" films that didn't have at least very good acting, since actors are such key elements in (at least traditional, and not avant-garde) film. Also, you've got to place some of the blame on the acting on the director, don't you?
Well he did say "directors have made great films without great acting" and now you're asking him to give examples of great movies that didn't have "very good" acting. Not exactly what he was saying.
I think lots of "great" films have serviceable acting that in no way approaches Academy Award winning level. In fact probably most of the favorite films of members on these forums. FOTR, Raiders, The Terminator, The Winter Soldier, etc. I absolutely would consider all of those films "great," with great directing, editing, casting even writing. But with regard to acting I think the actors in those films in a lot of cases coast on having great lines that are easy to deliver and great synergy with the rest of the cast. But a moment like Emma Stone's rant in Birdman? Or that one clip of Redmayne playing Hawking? Nah.
That's one of the reasons that I think that The Dark Knight gets such notice, because it's the rare "great" genre film that actually did have an Oscar caliber perfomance (Ledger.)