mattie b's relationship with his sister. >> i dedicate this song to my sister sarah grace. >> she isart and stuff. they's really funny. >> mattie b and sarah grace performed at the buddy walk, a fund-raiser for downs syndrome. she has been in his videos and one he dedicated to her has more than 12 million views on youtube. >> so beautiful. i tell her every day. >> of all of the things this kid rapper has going for him, perhaps one of the strongest is his love for his family and his determination to make sure people know that downs syndrome doesn't hold you down. >> my sister, she is in a normal classroom at school. and she does all of her homework, she does everything. she also knows some of the lyrics to my songs. >> scream and shout. >> let it all out. >> make a hit with mattie. >> she is as sweet as he is. thank you very much for letting me tag along, you know. i went over to where he was having a concert at the georgia dome, a couple weeks ago. >> look at you and mattie b. >> i'm squatting down. i'm not that short. he is tall. he will overtake me. >> also got the pop star hair sw

>> signs is invisible today. 11-year-old internet sensation matty b.has received millions of youtube views for his covers of popular rap songs in a squeaky clean kid friendly way. here he is doing jay-z's and rihanna's run this town. ♪ ♪ ♪ we're going to run this town ♪ meet me generation ♪ all black everything black ♪ getting ready for originals ♪ now i'm going for a feeling i forgot about ♪ ♪ on my way to the top, shortly says she's got a boyfriend ♪ ♪ our society is wonderful. here he is doing chris brown's loyal minus the n. word ♪ ♪ ♪ i ain't lying though ♪ ♪ ask that nerve you all about her ♪ ♪ but she's such a big flirt ♪ you will be doing all right if you ain't tricking yet ♪ ♪ that girl ain't loyal ♪ that girl ain't loyal ♪ wow we need to see much more of that. can we cut more tape, please? maybe ten seconds would have done it. we didn't need that. would you buy stock in this boy sensation? >> no. >> no? >> by the way i, i don't think he's 11. i think he's four years old. >> yeah, he looks very young. he's a young 11. by the way, isn't 11 like