Here's the text of a Norwegian article that purports to talk a director of communications at Nike about the commercial. I can't really speak to the veracity of this article, though, and the title is certainly deceptive.
Ronaldinho admits cheating
By Ole Kristian Strøm
Published 18/11/1905 - 6:49, modified 11/18/2005
Ronaldinho himself, according to the
BBC and several other sites, claiming
that everything is authentic.
In the commercial for a new Nike
soccer shoes nullify the Barcelona
star, apparently the laws of physics.
He bangs the ball on goal, hitting the
crossbar - and the ball comes back to
the Brazilian, which dampens it, and
continues to perform tricks.
Four times in a row.
"It's a pity to reveal, but where he
hit the crossbar four times, we've
been playing around with some digital
solutions," said Vita Clausen,
director of communications in northern
Europe for Nike.
Got help
"If there is a football player who can
do something like that, it's
Ronaldinho. He is a wonderful and
magical footballer. But in reality, a
man inside the line and kicking the
ball back to Ronaldinho. But he
actually hit the crossbar twice in a
row while shooting," said Clausen to
dr.dk.
Nike has since cut off the man, so we
only see Ronaldinho as juggling. The
debate has raged on the Internet.
Ronaldinho himself has on several
websites cited in the following:
It's true. It is not cheating. I usually tend to shoot the ball so
against the crossbar in the course of
training. I only did what I usually
do.
Is impossible
It was not meant that there would be no advertising. It would just be
something that people could enjoy on
the Internet.
But then it that is so, and this I am
proud of.
Zinedine Zidane has been quoted as
saying that "this is impossible."
Promotional clip is as follows:
After trick their way to the middle of
the 16-yard box, Ronaldinho bangs the
ball towards goal. It hit the
crossbar, is in a beautiful arc back
to the Brazilian, which dampen the
ball and continues with no tricks.
Then again, he sends off a rocket on
goal, the ball hit the left crossbar -
and goes back to Ronaldinho, without
having touched the ground.
How's also a third and fourth time.
Here's the source of the article, from Denmark's national channel.
That is as close to any official word on the commercial I've found. It seems to me it would be easy to film the player shooting the shots and have a digitally removed person throwing different balls back to simulate the catches. That would also explain why the ball does come back to him a bit quickly. So if the video was trickery to start with, there'd be little point in anyone trying to replicate it without trickery.
(And WOW... The new contextual translating Google does is pretty amazing. There are still some rough spots, but... WOW.)