There's a bunck of videos available, including the original, but Dan's "Monkey Business Illusion" is also well worth watching, even if you've seen the bear version and think you know what's going on.
There's also a whole book on the subject.
This experiment reveals two things: that we are missing a lot of what goes on around us, and that we have no idea that we are missing so much. To our surprise, it has become one of the best-known experiments in psychology. It is described in most introductory textbooks and is featured in more than a dozen science museums. It has been used by everyone from preachers and teachers to corporate trainers and terrorist hunters, not to mention characters on the TV show C.S.I., to help explain what we see and what we don't see. And it got us thinking that many other intuitive beliefs that we have about our own minds might be just as wrong. We wrote The Invisible Gorilla to explore the limits of human intuition and what they mean for ourselves and our world.
This has a wider importance than simply scientific research though. As a sometime bicyclist, EoR is well aware of how invisible he is to drivers.
Most people believe that unexpected or unusual events draw attention, perhaps even more than typical events. Why? In part, the belief is based on our experiences. When, on occasion, we happen to notice something unusual or unexpected, that event is remarkable. We take mental note of it and remember it. When we notice a typical or expected event, that’s unremarkable. Critically, we are, by definition, unaware of any events we don’t notice. If we fail to notice unexpected events more than expected ones, we won’t be aware of those probabilities. (...) A 42 year old bicyclist was riding down Highway 18 in the Town of Summit (in Wisconsin) when he was struck from behind by a 20 year old driver. According to the article, police are still investigating why the driver didn’t see the cyclist, but Officer Dana Hazelton noted that bicyclists rarely ride on the highway because “There’s actually a bicycle trail that’s just south of Highway 18 that’s probably 20 feet off the road that’s made for bicyclists.” In other words, people don’t expect to see bicyclists riding on the side of the highway, so they are less likely to notice them.