The film has been on for an hour.

[Alice Chu]

1. The film has been on for an hour.
It means the film started an hour ago and is still on.

The two sentences below are incorrect because the action of beginning or starting is completed in an instant and cannot continue.
2. The film has begun for an hour.
3. The film has been starting for an hour.

 

[emsr2d2]

Yes.

 

[teechar]

I'll just add that #4 might work in some limited contexts. For example, they announce that the film is starting, but an hour later the audience is still waiting. This is similar to your other thread with "has been leaving for an hour".

 

[emsr2d2]

I wouldn't use "has been starting" even in teechar's context. I'd say "The film was due/supposed to start an hour ago but ...". For me, the film starting is a single event so it can't be spread over a duration. The film has either started or it hasn't.

 

[teechar]

It could be someone in the audience making a wry comment.