Upon playing this video, the introduction warns the viewer as follows:
Be aware! This video may cause temporary hallucinogenic effects. But please do not be afraid, these effects usually last a few seconds.
The warning is overly dramatic, but it does produce a pretty amazing effect. And in case you are worried, rest assured that this is not some sort of joke or trick where a scary face will pop up on the screen screaming at you in an effort to make you fall from your chair. If you do happen to think these are funny, however, you can watch a couple of kids getting scared by one here.
When I tried it, everything I looked at for a few seconds was swirling around like crazy. Did it work for you?