This has nothing to do with the Washington Redskins. This clip is from ESPN's College Gameday show, which is set each week at the location of whatever game is deemed to be the biggest college football game of the week, in this case between the Florida State Seminoles and the Clemson Tigers.
The music you hear is from the Florida State "Marching Chiefs" band. The booing, and later the cheering, that you hear is from the Clemson fans who have assembled around the set, and who view the fake tackling and stomping of Corso as symbolic of what their team is about to do (they were hoping) to the Seminole football team (Didn't work out so well in that regard, as it was Clemson who got stomped 51-14).
P.S. - small correction to your post below. Bob Costas works for NBC/Universal, not ABC/ESPN.