This is a good example of a "forced" or "assisted" conversion. The user really doesn't want to do it, they just want to view the damn YouTube video.
Google is employing these same optimization techniques elsewhere. I've noticed very subtle, and consequently expensive, things that have been done with Adwords.
There is a simple solution to this, which unfortunately castrates Google's entire platform. Its the same reason why I've been avoiding Android. It is also why I have to tell my friends I can't view their Youtube link because it says I have to sign in.