[mikece]

Personally, I would ignore it. If they're an over-performer and taking a brain-break then it won't affect their productivity. If they're a slacker anyway then it's a matter for management to solve. The larger problem would be if the person is an under-achieve, management knows, and they do nothing. In this case the video game playing is the symptom of an organization with management issues.

[uberman]

The player is the co-founder, not a co-worker. Does that change your recommendation at all?

[nightfly]

Why should it? Founders aren't robots

[uberman]

Since they are a co-founder, who is "the management" that is going to see individual performance issues and solve them? I hope you don't think that "the board" will know in a vacuum that an individual is underperforming...