In this exchange, Mitt Romney is seeking to take the high ground by saying that he left public office to pursue private sector experience. Both Santorum and Gingrich call him on it.
Santorum then goes after Romney for not running for reelection in Massachusetts as Governor:
In this exchange, Newt again rips Romney, this time for the negative ads. David Gregory asks Newt if the latter is willing to stand by his claim that Mitt is a liar. Romney was place squarely on his heels here:
This video includes a portion of the above exchange but with more fireworks from Newt:
This happened after the debate. It was an exchange between Chris Matthews and former New Hampshire Governor, John Sununu, who appeared more than just a little agitated. It's possible that Sununu, a Romney supporter, didn't like the attacks other candidates levied against his choice. The Meet the Press debate was not a good one for Romney and Sununu seems to reflect that.