Thats called "The Dance of eternity" off of metropolis part 2. DT is fucking awesome. Ive seen them twice in concert and ive never been more blown away. If you wana see a good show go see them.
Also if you like them check out "liquid tension experiment", its there project band without a singer. Songs such as "paradigm shift", "universal mind", "when the water breaks"
Im kinda a rediculious dream theater fan.
Actually now that im watching it at 8:28 that start playing paradigm shift from there Liquid tension experiment album as you can see by the image on the backround.
Now that im watching even more its the "instrumedely" (just correcting title as its not intermedely) off of the "live at budokan" album. Fucking sick album.