In short... The Tribeca Film Festival and American Express are now accepting pitches via their My Movie Pitch contest on YouTube. Winners will see their pitches made into short films that will premiere at the 2012 Tribeca Film Festival; and in addition, you’ll win a trip to NYC for the film's premiere.
The 2 videos below explain the program; and the 2 videos at the bottom include the last winning pitch, as well as the short that was made based on that pitch.
Here's the pitch that won, referenced in the first video above:
And here's the short film that was made based on the above pitch: