Chester is playing a slot machine at the Longbranch with Matt looking on. Matt is resting a hand on the slot machine and Chester is not. In the closeup each character is resting a hand on top of the machine, two hands are seen. But only Matt is resting his hand there when the camera pans out and also his hand is clenched. It was not clenched in the closeup.
Chester is playing a slot machine at the Longbranch. But slot machines hadn't been invented yet. The first true slot machine was developed by Charles Fey, a San Francisco mechanic, in 1895.