I've wondered about the AR cards myself, can't imagine there's anything particularly special about the cards themselves.
As far as the nintendo video deal goes as far as I can tell there is no way to actually choose what type of videos it gives you the choice of downloading; seems more gimmicky (hay guis i haz videoz on muh ds lol!" than anything.
On that note I ran across what would appear to be a program for converting videos to a format the 3DS can play. Haven't tried it yet but looks promising; http://gbatemp.net/topic/315365-3ds-video-beta/
"I think that the problem with this video is it is highly derivative of many popular bands within the genre. Although when viewed on its own merits, it does have a deeper groove. However what it has in groove, it lacks in originality. One can't help but be reminded of such bands as Pearl Jam, White Zombie, Suicidal Tendencies and other bands that bear the mantle of so called "Alternative Rock". One is even reminded of Lorie Anderson when she wore curlers. Hehehmhm! This video speaks less to the heart and more to the sphincter. In closing, I think Korn would do well to learn more from -"