As for why people believe the landing was a hoax... I've always been of the opinion that if we really did land on the moon, it means that the world/universe is much bigger than these folks can handle.
Some of the most vocal hoaxers that I've personally met have never been far beyond the city limits of their home town. They have trouble grasping the idea that there's a whole world full of people out there. And they're genuinely freaked out by the idea that there's all those billions of light-years worth of space around us. I think it is easier for them just to think of the moon/sun/stars and lights in the sky.
I'd disagree on that. Of course, it all depends on what sort of people one meets, but the moon hoax proponents I know, seem to be also general conspiracy theorists - they find it more plausible to assume that the public is manipulated by some hidden forces behind the scenes.
Once this point of view is taken, it's just a matter of looking at everything and spotting details that could support their theories.
And the Moon landings lend themselves quite easilly to such a scrutiny, as there is very little easily accessible data on what was really going on, both from the scientific and organisational side.
If one doesn't know the science at work - which can't be really intuited from our everyday lives in this case - how can he judge if what he sees on those videos is realistically possible?
If one doesn't know what techniques were used in between the pictures/videos being taken, and the publication/broadcasting, how can he judge the source of artifacts he spots?