A heartwarming video has emerged of a man proposing to his girlfriend in a cinema after expressing his feelings for her through a fake advertisement video.

The footage, shot on March 16 in Vancouver, WA, USA, captures Adrianna Neil's reaction as she realises the trailer is about her and her boyfriend Ryan Langston.

As the clip finishes, Langston kneels down and hands a ring to Neil who accepts the proposal and jumps in his arms as the crowd cheers.