Above, the first video I saw on this YouTube account about an hour ago. Here was the second, here was the third, and the fourth, and the fifth. Wait, don't miss this one either. You kind of need to just take some time and watch all of them. Also this.
Nadja over at Street Carnage says,
[He] looks like he might have Progeria, a terrible disease where your body is elderly even though you're only 8. Regardless of this disfiguring disease, he's a true gangster. He has the balls to go online and be like every other pre-teen boy on youtube, singing along to Papa Roach and generally being awesome. The fact that he does this, that it brings him some kind of happiness, and that he calls himself "chick3n little", is why the internet is amazing and why the world doesn't seem so shitty sometimes.
I am not a doctor, and I do not know what condition the person in the video has that makes them look and behave differently. But here is the Wikipedia entry on Hutchinson-Gilford Progeria Syndrome ("Progeria", or "HGPS"). Here is another entry for a different condition called Virchow-Seckel Syndrome.
Looks like the content was previously uploaded to YouTube under another name, deleted, then re-uploaded them under this new account name. His real name is apparently Justin?
Update: Some background on the meme provenance in this BB comment. Some have stated that the current YouTube channel is not controlled by the person in the videos, but was reconstructed by someone else. In other words, the videos appear to have been created and originally published online by this young person, but the "Tsimfuckus" YT channel, and the descriptions/titles therein, not actually his. Various accounts name the person in the video as Justin Tsimbidis; he called himself "tsimfuckis"/"tsimfuckus" in one of his videos. The uploads are fascinating, but it sucks that anonymous jerks on the internet are being cruel to this person.