I've never heard Obama say anything about Paul, anywhere. I think he pretends like he doesn't exist because he hates his guts. Obama doesn't want people to think about Ron Paul, he doesn't want anybody to know that he exists. Just like the media. Ron Paul represents everything that Obama is not, in every way. Obama is scared of Ron Paul because he knows that Ron Paul would destroy him in debates and in the general election. Obama would much rather face off against a more left-wing establishment candidate like Mitt Romney or Newt Gingrich. The reason is because they are simply easy targets with a lot of skeletons in their closets. Obama would not be able to come up with anything on Ron Paul because his record is squeaky clean and has been totally consistent. This is all speculation of course. What do you think Obama really thinks about Ron Paul?
This is just a guess, and it's probably a projection of my own thoughts, but I suspect that Obama thinks that Ron Paul has a number of great points, a few serious disadvantages, and no real election prospects other than as a spoiler.
He's not concerned because Ron Paul is unelectable because people keep saying he's unelectable. If he was electable (which would simply take people to stop stating he's unelectable) then he'd be a serious threat because he is the only GOP candidate who could and would actually take votes AWAY from Obama rather than give them to him.
I think he listens to Ron Paul's views.. because RP really does think outside the box. There is value in that.