What's Backseat Gaming?
Backseat gaming is much like backseat driving (which I believe the term derives from).
Unless expressively asked; telling the player where to go, how to play, the best way (and the truth) and when to do it is effectively backseating. In some cases spoilery tips can (and in some parts of the web are) sometimes still considered by many as such despite the potential well intentions.
Try to avoid this, it spoils the experience for you as well as me! It's not a walkthrough and there are plenty of those on the interwebs already.
Watch the commentator / host succeed, fail, miss, find & improv. Warts an all. Enjoy the ride, chat with the host / community and chill! ;)