Its Probably the app its self crashing, they need to come out with a patch for it, hopfully it will be soon but i have heard lots oh bad stuff about the youtube app on the 3DS
if you want you can read this fourm and see if you can get some help from it
http://nsider2.com/forums/index.php/topic/603133-3ds-youtube-app-errors/
click for solouion