Watch full video for info about how it's done and how to do it.
This isn't a hack and I'm not a cheater. I didn't use any external program to modify the game; anyone can do this.
And for the record, I figured it out myself: I didn't look it up online. Figuring it out was half the fun : )
It was very interesting to see peoples' reactions to the infinite uber. Most people assumed immediately that I was hacking (I guess we have an assumption that software is inherently bug-free?) Once people realized that I was infinitely ubered, a surprising number of people still tried attacking me. My theory is that either a) they thought it might be a graphical glitch (not interesting), or b) once one rule of the game was broken (ubers only last 10 seconds), other players assumed other rules might be broken too (for example, an ubered player might be somehow killable.)
I tried this on Well once just to see if I could survive a train. The answer is no.