I think that the people who your talking about (Being A-listers) will most likely respond to your inquiry as they do any other time someone tries to proposition them...
Which happens every day of their lives...
If you have a film that is great people will notice that on it's own and then they'll be the one's contacting you.
Ah, I must have misspoken. I'm not trying to make a 'proposition'. In fact I only wanted to say hi, maybe start some small talk about something I noticed on their profile. I know how it works out there ( I live here), the last thing they need is some punk amatuer bugging them about a project.