Proof of winnings -Non US citizens

[JAque]

I was asked by a friend that plays the biggest games on line if the casinos provide any kind of paperwork about his winnings. He lives outside the US and his bank is asking him of proof for where the money is coming from. He probably makes wire transfers in excess of 5 figures a month.

His accountant told him that all gambling companies have a way to do this so their customers are not suspected of money laundering , terrorism , etc.
Computer log files of screen pictures are not accepted. It must come in a form of a letter from the site, he was told.

Does anyone have any experience with this?

Thanks

JAque