Listen carefully to Doctor Carson. He speaks truth to many things: political correctness, value of education, importance of parents to children. Notice how uncomfortable Obama seems, as he withholds applause when the rest of the audience applauds. Then as Carson starts speaking of ancient Rome as a warning to the US (at 17:24), I detect a bit of a "presidential glare". At 21:28, when Dr Carson starts extolling health savings accounts, Obama looks positively glum! At about 24:22 the clip is accelerated a few seconds; I don't know why.
In many ways, this is reminiscent of the 1994 Prayer Breakfast when Mother Teresa told the audience, including then-president Bill Clinton that "the greatest destroyer of peace is abortion".