They are airing this again on 9PM Saturday. I've seen this in the past, not sure if it was last year or the year before. This is by far the best documentary on 9/11 I have seen, if you haven't seen it before I'd strongly urge you to watch it.
It's about 2 hours long with no commercials. There is no narrator, the footage consists entirely of home/amateur video. The editors of this did an incredible job putting this together.