tube. singer and personality known as joshua d-town with a huge following of his own. mass majority of our audience is 13 to 21. tried walking with them at a mall. always look at the camera. reporter: in 30 seconds you i will see, sure enough some high school kids recognize him. i know him. that s hilarious. reporter: hi. i m david at the l.a. county museum of art. they showed me the dos and don ts of blogging. my arm is sore. is that an occupational hazard? yes, it is. reporter: david wright, abc news, los angeles. i d watch david wright s you tube channel. that s one of the things in life i don t understand. what s that? you tube, the phenomenon known as you tube. the phenomenon. when are you going to figure this out? help me out here. help me out. to figure this out. help me out here. help me out.