The proposer's own words describing video on YouTube:
My girlfriend Ginny gets taken to the movie theater to see "Fast Five". After a preview for the Hangover 2, a trailer for a movie comes on. A trailer I made of her father and I where I ask her father for her hand in marriage. After he gives me permission, I race off to the theater she is at to ask her to marry me. What she doesn't know is our familiy and friends are in the theater with her watching the whole thing, along with about 100 strangers ;-)