You know, my gut tells me a walkthough is better than a general gameplay video. If you can do a walkthough of a difficult level, that could be helpful for some people LOOKING for a walkthough of a difficult level. In the 90's all we had was magazines to read walkthroughs, and sometimes text guides. Video walkthroughs have helped me a lot in the past, especially on BioShock.
So it might not have fast view potential, but it can definitely have long term evergreen potential. People still play unpopular games. Like, Half Life 1 is SUPER old now, but people still play it sometimes, and those people still might get lost on a level. So I see nothing wrong with a walkthrough. Though simply watching someone playing a game for the sake of playing has limited watch replayability.