OK, so regardless of what people think of Metallica now after their change in musical direction, and the more recent Napster events, there's no denying that One is one of the best songs ever made. And the video...
The video centres around a similar theme to the song. A young man goes off to war, and comes back with no limbs, unable to to think, basically a vegetable. The song explores the man's hopes of dying, and the pain he's in. The video is very unique in it's style, mixing film of Metallica "jamming" in a city warehouse, and footage of a little known film "Johnny gets his gun", which Metallica bought the rights to so they could use it in the video. The howling of the grenades and mortars in the video perfectly complements the sultry guitar playing and lyrics of the song.
This particular video also features an 8 minute interview with Lars at the beginning, complete with obligatory 80's metal haircut. Then the "One" video is shown, followed by the "Jamming Version". This second version of the song/video is rubbish. Metallica themselves were reluctant to make this version, but had to due to radio and TV presures (the full-length song was too long to play on the Radio or MTV), and contains only the band playing in the warehouse, but actually misses a lot of the song, which I think takes so much away from the atmosphere of both the song and the video.
The original version of the video though, is a classic and if you are a fan of Metalica, you WILL want to see this video. No debate. And as for the question of money, £6 is well worth it for the original version alone.