You won't get a unifying, definitive answer to such a thing. The Bible doesn't give specific guidelines as to what we're supposed to be entertained by, so it's pointless to delineate between particular genres or subject matter because every opinion of what's "okay" by the vague standards of the Bible (e.g. Philippians 4:8) is completely subjective.
Take a film like, say, 'The Little Mermaid'. Some will say "well, it's a G-rated Disney film, so that's okay for Christians to watch", where as others will say, "but it has depictions of evil and the supernatural, so that's not okay for Christians to watch"...it's the same kind of contradictions and double standards as with music (e.g. christian rock only vs. no rock music at all, etc.). I don't think there's any one film which has unanimous Christian approval; even 'VeggieTales' gets criticism from more conservative religious groups.
I honestly don't believe ratings or content matter all that much, but rather the message the movie's trying to get across. There are a lot of films which glorify crime or drug use or general unlawful behavior, and I'd consider that inherently "unChristian" viewing. Although, mere depiction doesn't mean glorification: for example, a stoner comedy promoting the use of illicit drugs and excessive drinking is very different from a film like 'Trainspotting', which features the same albeit in an effectively negative light. Likewise, nobody's going to watch 'Goodfellas' and be inspired to join the Mafia because none of the characters get a happy ending at the end. A movie's morals are more important than its content.
God helps guide our conscience and drive us away from things which are objectionable and undesirable, but ultimately, if something makes you uncomfortable for any reason, don't watch it. If anything invokes a feeling in the back of your mind that you shouldn't be watching it, that's your reason to stop, not any arbitrary rules suggested by random people on the internet.