There’s nothing for him to gain by doing so, in the interview he actually reveals a little details about the planned Sonic title that was in development. To better visualize this concept into people’s minds, the best option’s always video.

Bah, I’ve seen more convincing fakes in the past.

I severely doubt it’s fake, as Sega-16 is a incredibly reliable source for all things revolving the Genesis. Keep in mind this isn’t as if they received that Sonic prototype movie from some random homebrewer, that’s far from the truth. It was an exclusive provided by Peter Morawiec, an ex-Sega programmer who worked on the game himself before it was denied by Naka.