The Italian commentary makes it seem like this was an "in joke" rather then a serious show of disaffection. I don't think this is really a story.
What were they saying?
The look on they guys face doesn't look like it was a joke
Exactly....didnt look anything like a joke to me.
I had a quick look on the AC Milan and luckily being black and at an italian team there wasnt many people it could be. The guy Strasser Rodney who is apparently a 19year old from Sierra Leone.
It also helps that it tells you his name in the title of the Youtube video.
What were they saying?
The look on they guys face doesn't look like it was a joke
I don't know when the commentary says "Its a joke" maybe?
Also if you look at what happens after the kick, Ibra goes towards Ronaldinho and shares a couple of words, in a affectionate matter. It was probably a practical joke in which Ronaldinho was almost certainly involved in. This is backed by the italian commentary as well.