You owe it to yourself to mainline some of the emotional power of opera. This appears to be a piece from Les Miserables put together by the Obama national campaign staff UltimateImprov, self-described as "a small comedy/improv theater in Los Angeles." (h/t ngack in the comments)
I'm not familiar with Les Miserables beyond the most general of plot lines from Hugo's novel. I trust the cultured among us can provide appropriate parallels. I was advised by the person who pointed me to this that it's best to forget that the upper-class students, shunned by their parents for their liberal views, all get shot and die at the end of the opera. History treated the revolutionaries better, I think.
All I know is that after watching this, I feel something stronger than blood flowing through my veins. Man the ramparts phone banks!
Update: I found a link for lyrics. Besides getting a little clarity for what's happening, it gives a bit more of a who's who.
Final reprise (timeline--Nov 3):
ALL
Tomorrow we'll discover
What our God in Heaven has in store!
One more dawn
One more day
One day more!