Most everyone I've talked to feels this was by far the most moving of the Animatrix shorts. I wholeheartedly agree, but I wasn't sure why at first. I think I've figured it out.
We all have those beautiful moments in life that surprise us, overwhelm us, and then just disappear. The problem is that we as humans can't really communicate experiences with each other. The best we can usually do is vaguely explain the circumstances of an experience and hope to trigger memories of that experience in someone else. It still only works if the person has already had the experience. If someone tells me about their first love, I can only understand it by remembering how I felt during mine. If someone explains what it's like to be abused as a child, I really can't relate no matter how well it's described.
There is, however, a good trick that can be used to convey feelings. Use a fictional but literal description that should provoke the same feeling. For example, to describe heartbreak, I may say it felt like someone ripped my heart out and kicked it into a trash can. Hopefully, you can imagine this literally happening to you and end up with the same feeling as I have.
This is what "Beyond" does. It describes what it feels like to experience beautiful human moments without requiring very specific empathy. Sometimes, with the way they make us feel, the moments we experience might as well be glitches in a perfectly running computer program that we bumble into and are deleted from under us just as quickly. Even an alien who only vaguely feels awe and wonder at the possibility of physics breaking down elegantly for a short time could understand the excitement, awe, and sadness that a human feels every few years, if one is so lucky.
