Check out this video we got -- Ben was at the Wynn Resort and Casino early Wednesday morning, standing alone at a table ... just the dealer and him. Unclear what game he was playing, but witnesses tell us he was in the high limit room. Naturally.
We're told casino staff was standing guard to shoo away any fans who happened to notice one half of Bennifer laying down bets around 3 AM.
The witnesses say there were no camera crews during his time at the tables ... an important detail, because Ben is actually working in Vegas too. We got more video of him Wednesday afternoon shooting something over at The Palazzo, but we're told the actor shot a ton of other scenes in the working casino, too.
You can hear someone yelling, "action" as he started walking through the casino, but a source tells us Ben is also directing the project.