This is probably one of my largest complaints about a google product at the moment. It feels like they're trying to trick me in to doing it with that invasive pop-up I get every week.

I don't even use YouTube for uploading or commenting, but I also don't want my real name and a photo of me on that site in any form. There's always the small chance they'll do something stupid like roll an update that makes my "previously viewed videos" available to my "social connections" by default without notifying me.