> In other words, it seems arguable viewers view for the games more than the Let's Player. If people would tune in without the games then there's no reason for the Let's Player to have the games at all.

Successful Let's Play personalities like PewDiePie or Markiplier, or even the more critique style of TotalBiscuit, tend to get very similar video view counts if they're covering a $2 indie game versus if they're playing some $60 AAA title. I think there'd be a way bigger difference in video view count if the specific game being played was particularly important.