It's from Fahrenheit 9/11 (I didn't care for the film that much, mostly because I thought it was not so well done.)
This is at the end of the film, with scenes from the film shown around the music. I had heard that Micheal Moore wanted to use the song by The Who, Won't get fooled Again, but didn't get permission from the rock band.
Neil Young was willing to let this song, written at the time of G. Bush Sr., to be used. (By the way, I think Sr. was a much better president than Jr.)
Anyway, here it is.