What I think Will means by "Romneyness" is that he is a technocrat like Obama. The "I will get it done because I'm Mitt Romney--trust me" kind of attitude.
As Will says, it's interesting that our "most electable" candidate has 6 wins and 19 losses in his last 25 races.
UPDATE: Vid fixed.
Another State Democrat Group Drops "Jefferson-Jackson" From Annual Dinner Title | Christine Rousselle