Watching a real life version of Escher's Impossible Waterfall melts my brain. The more I look at, the more confused I get! Thankfully, the secret on how the whole illusion works is out. There's clear DIY instructions on how to make your own impossible waterfall on Instructables and that video above shows what's really going on.
Note: It's not a walk in the park to make. You'll need to string up PVC tubes and an electric water pump, use angled grinder and glue guns, and most importantly, film the whole setup at the most perfect angle to complete the illusion. Well worth the ensuing friend brain meltage though. [Instructables]