500 Days Of Summer Split Screen

Hero - (500) Days of Summer from Music + Films on Vimeo.
When I thought of the idea for having a spilt screen to show what would happen when an event goes wrong, the first scene that I thought of first was the split screen in the film '500 Days Of Summer'. This scene also plays with the thought  of alternate ending, however this uses the expectations of a man (Tom) vs the reality of what is actually happening after he gets invited to a party by the woman he is still in love with. In one scene he ends up with the woman he wants, however in the other he finds out that she is getting engaged, this being the reality side.
What I love about this scene is how easy it is to follow, my fear for my work would be that if two scenes are playing at the same time how can you watch two at once? I figured like what they do here, a major event  could be happening while in the other eg a man is waiting outside a lift waiting to get on etc