part of a star-studded lineup performing for president obama, the first lady and the first lady's mother. among plenty of other guests president obama called gospel music unique because of its unmatched power. the event was part of the pbs series in performance at the white house and it will be broadcast in late june. >> one of the great things maybe good or bad, depending on who you are, about everybody having a camera in their pocket now is that you catch a lot of stuff on camera, some of it odd, some of it embarrassing and we end up putting it on national television. that's a problem. this morning's example takes us to buckingham palaces in london. >> during a changing of the guards, one loses his footing and ends up on the ground. he slipped on a manhole cover that's inconveniently located right in front of that sentry box. >> the guy kept a stiff upper lip. he's holding his weapon. he immediately gets back up. now he's getting a lot of attention. several soldiers pass by as if