Okay, stop. Usually, I take a pretty laid back approach on this, but this completely misses the point.
This is more serious because the we now have a whole game out on the market for all to see without playing three months in advance. In essence, this cripples potential sales of the title and, more importantly, casts doubts on Sega to ever try a project like this again (which I understand that even getting this thing green lighted was a pain because Execs weren't keen on the idea).
Long story short, kiss 2D Sonic good bye. All because the fans were too damn impatient and someone broke NDA by serving as a third-party and actually GIVING out the videos. This case is so severe, PartnerNET has been shut down. This has never happened at this level before and with an anticipated major multiplatform release.
Quality of the title because no one in this topic is qualified to talk about it (and kill yourself if you say you are just by staring at videos) is completely separate to the case here.
Please. You're starting to sound like the admin goons over at Sonic Retro, at this point. If you choose to blame the "leaker" and those who gave him attention, to me, you're still missing out on the main thing. Leak or no leak, the game itself, and its inherent quality there of, is still the centerpiece of this menagerie.
And that's the basic thing. The video could have done so much more to "make the case" for the game. If the game played well (the main thing that was important), and really did more to prove that "Blue is Back~!", then huzzahs would have been uttered and people would have been happy to wait 3 more months to get the game for themselves. And since there's no Pulitzer-level story line being leaked, the only thing that has been spoiled are stage gimmicks, bosses and the like.
So, far as I'm concerned?
This is no different from how, especially many years ago, it only took one importer to obtain a Japanese release of a game, many months to a year before the Western release, and spoil the entire contents of the game itself for non-importers/-Japanese speakers. Everything about the game would be laid bare, and then it'd just be on the other users to decide if they still want in or not. Fundamentally, that's all that's going on here, too.