Frank Zappa's Black Page 2 is one of the most confusing songs I've heard, I still can't quite get through it on the drums lol.
YouTube - Frank Zappa - Black Page #2 - 1981

This is awesome, this guy (That 1 Guy) is a classically trained celloist, and made his own instrument because he got bored of the cello. The pipe he's banging on is the instrument, it consists of cello strings, electric drum triggers and who knows what else.. Really amazing stuff, especially the live performances. His music reminds me of Frank Zappa's in that it is incredibly serious and complex, yet the lyrics are anything but serious.
Mustaches-http://www.youtube.com/watch?v=0XHt32UVqLk

This is the Frederik Thorendal from Meshuggah with drummer Morgan Agren making one of the most interesting things I've heard (listen to the cymbal and snare in relation to the guitar). I don't care if I have posted this before, it still blows my mind how complex the rythm is.
YouTube - Meshuggah (Fredrik) + Morgan Incredible Medley

This one just goes to show how deep Tool's music really can be, the song is called Lateralus (lateral-us) and is pretty much about life, and how capable a mind can become when pushed.. encouraging the listener to embrace new ideals, thoughts and levels of consciousness. The song is written in the fibbonacci sequence (each number is the sum of the preceding two, 1,1,2,3,5,8 etc.), a naturally occuring (shells, flowers..) phenomenon. Not to mention Danny Carey is one of the best drummers around and this video is full of Alex Grey's art.
YouTube - Tool - Lateralus

Enjoy! Feel free to post more epic videos of any nature, I love threads that keep me busy lol.