It does not disappear in either of those. At :33, you can see it just behind him on the left side of the screen (his right) in the milliseconds afterwards. At 1:01 you can see it in front of his jersey at about his stomach. Try putting it in 720p for a bit more resolution.
This is filmed on some lower end point and shoot camera or cell phone, so the lines of each frame are recorded top to bottom (making for a jiggle when panning) instead of all at once, so fast moving things (such as a basketball being released after a dunk) can be distorted/not show up where you'd expect them too.
Its not faked
Oh, and impressive dunking skills. Wish I could jump like that