I agree that someone whose information is all second hand is usually not as valuable as an informated first hand account. I just want to add that even someone who views a game may not have valuable input. We have no idea about the person's ability to know what is really going on in a game. An unskilled eye may make a false assumption even though they watched the game.
For example, a person may blame a blocker for a failed running play, when, in fact, the culprit was the impatient running back who didn't wait for the play to develop. On the other hand, the person might get it right. You never know the quality of the input unless you have previous verifiable examples to trust (or not trust) the poster's opinions.