Populism is an odd fit for Mitchell, as is apparent partisanship, so maybe that's part of what's so weird about this clip. It might be that he keeps interrupting her, but everyone on cable TV interrupts each other. (Whether interruptions vary by gender, I can only guess.)
But it's the way Steele keeps repeating her name, though, that seems to profoundly irritate Mitchell. During a dozen exasperated "Andrea" repetitions, she gets in "Mr. Chairman" and then a very pointed "Sir." Is she just fed up with him refusing to properly answer her questions? Or is this a case of familiarity pointing to a mild form of disrespect, the way in the primaries Hillary Clinton was always Hillary and Barack Obama was always Obama? (And yeah, sure, there was another Clinton with whom you could be confused, but this tends to be the case for plenty of women in public life.) Then again, every TV personality is known by their first name.
Or maybe, like most people, she just thinks Michael Steele is completely ridiculous.