All dislikes gone on youtube!?

Looks as though every video on YT has had it's dislikes reset!? I started noticing it last night. Even Rebecca Black's "Friday" appears to have 0 thumb downs which as we know... isn't possible. I wonder if this is a temporary glitch or someones hacked them?
Really weird in any case.

UnderdogElite (Heavy Music)

Kerls House (Animation & Gaming fun)

Toys with Tommy (Comic toy reviews)

Galactic Kay (Kerls House)