Are we talking about one of
these kinds of finger-rolls? Or the one that happens
here at about 0:11?
There's another one at about 3:03, another around 3:20, another about 3:31, another at 4:01 or so...
The finger roll is situational and can be fired off in a variety of ways; some of them are not at all about hand size or finger length but rather about the wrist snap and how you send the ball off your fingers... kind of like juggling or spinning tins when you bartend.
It's a finesse move and it is sort of a cousin to the floater in a way, since it's about getting the ball over your opponent with good touch, rather than a power move going through him. You can use arm extension through slots in the defense through which your body can't fit and that makes it a great weapon for getting a shot closer to the rim than you can get if you just stop and jump.
Plus, if you've got the hands for it, you can do the uber-move.
Start on one side, drive diagonally towards the other side, bring that ball out palmed in your hand, then turn your wrist and flick... it's unguardable, the defender can only foul if you get that first step.
Iceman was the king of the finger-roll; it's a bit of a lost art, really, because people go to the floater a lot more but you get more control with a real finger roll than with a floater.