Only things that really matters in game footage is video quality and audio quality. If either is, how would you say, is s**t then the viewer (I'm generalizing from my own point of view) will instantly leave. Bad "gameplay" can be entertaining, have a look at Happy Wheels for example.
As for content of commentary is entirely subjective. For example, me been in the late 30's demographic would be unlikely to like watching a young teenager horsing around continuosly, video after video. I'm guessing a teenage viewer would just eat that stuff up and think nothing of it.