Section I-Player The player is out-of-bounds when he touches the floor or any object on or outside a boundary. For location of a player in the air, his position is that from which he last touched the floor. [0]

[0] http://www.nba.com/analysis/rules_8.html?nav=ArticleList

Kobe Bryant shooting from behind the backboard in 2009: https://www.youtube.com/watch?v=KnARpfzVIis

It depends on how they picked the points where he 'took the shot from'. You generally don't take a shot from a standing position in normal plat, you jump. You might not always land in the same spot from which you launch.

I suspect they picked the point where he jumped from, rather than too, therefore you can run parallel to the backboard, jump under it (from behind, and land in front) and lay it up so it goes in.

Jump shots are taken at peak height. He probably jumped in the out-of-bounds direction for those and released the ball past the boundary line.

over the backboard on the way out of bounds probably