This is solid advice, also for playtesting video games as well. I definitely think the point about not being the one to teach the game to players, but rather l

This is solid advice, also for playtesting video games as well. I definitely think the point about not being the one to teach the game to players, but rather letting the rulebook do so, is important. You won't be there at every play session of your game, for every group that ever buys it. Additionally, having sessions where you can observe (either because they were recorded or you were there) are great, especially when you aren't interacting with the game, as this will prevent your biases or experience from steering the game onto already discovered paths.