This short is in many ways the opposite of "World Record". Where that film is based on an clever concept and idea, and totally wasted its potential, "Beyond" is based on a simple concept, and takes it, well, beyond what I expected (pardon the pun). World Record uses cold and surreal animation to tell a fairly real story. Beyond uses warm and traditional animation to tell a somewhat surreal and bizarre story.
In short, it is a work of contradictions. The story - and there isn't all that much of it, to be honest - is about a group of kids who find a haunted house (a glitch in the matrix) and accept it as perfectly natural part of their world, they enjoy the enchanted surroundings with the childhood innocence that they still possess.
I can only recommend this short movie - after "Kid's Story" it is perhaps the best of the Animatrix quickies. Fun, and enchanting.