I'd recommend this more for people who have seen Coldplay's actual music video for "The Scientist", because if you haven't it will probably be on the boring side. But it's paced really well and done in the same fashion as Coldplay's version. I like it a lot.
The best Lain video that I have seen has got to ben H E X by Machine.
Why? It is pure art, pure style, just like Lain itself. It has captured the psychadelic feeling of the anime. You know he put a lot of effort into it, but more than that it has a feeling of patience. It just feels like he took his time making it, thinking it over and didn't rush it. The images are beautifully chosen and manipulated to match the music at every turn. Also the inspired mix of background images and the ones that are at the forefront help heighten the mood to unknown levels.
This video is the definitive Lain video, if you liked Lain you're more than going to love this. It is the work of a gifted artist, totally original and totally genius.
This is a rather old video (entry number 1641 on the org I think qualfies here), but I consider it one of the classics that those who see vids made today really ought to see. It is asthetically wonderful and still I think has done the best job of imagry for this show. This was one of the vids that made me want to make AMV's.