Gondry - Yrdnog?

Was that YouTube a fake? A reader suggests it was filmed backwards, with artful passers-by walking backwards to convey the impression of it being in real time. What about his words at the beginning?

There's an obvious cut between it and the shot showing him solving it. With the addition of some background ambient noise, the whole thing is made to appear genuine. I personally think realising how it's done improves it; makes it more Gondry-esque.

Watching it again, it's clear my reader is right. Gondry has used reverse filming before. Here's the link.