From NBC's Andy Merten
Thompson's YouTube video was the first to go negative so far. It hit Romney on abortion and Huckabee on taxes.
None of the Democrats' videos did in their debate back in July, but that was early in the campaign and before candidates started taking swipes at each other. In fact, it was the last debate of this format that promted the first real spat on the Democratic side -- that between Obama and Clinton on meeting with foreign leaders. It'd be interesting to see if the Democratic version of this debate were held today, what kind of negative videos those candidates might submit.