It looks worse than it really is.
Some little white dude, Stuart Tanner, in a v-neck sweater managed to get himself on the court against the Nets' point guard, Devin Harris, for a brief game of one-on-one.
The video tells a tough story. Harris got the ball first, out of bounds, and missed a long jumper. Then Tanner nailed a tough fallaway, and then put on a little dribbling show before putting the ball through Harris' legs on his way to a layup and the shutout win.
The word is that the guy in the v-neck is actually a legend of London streetball, to the extent there are such things.