Two of my favorite things from 2011 Bonnaroo combined for a cool moment at the Outside Lands music festival in San Francisco this weekend: Mavis Staples' cover of "The Weight" and Arcade Fire.

AF frontman Win Butler joined up with the gospel and soul mainstay during her set, on The Band original. Sporting a stripey top and a colorful guitar, he sang during that well-known chorus. This fan-made video was just too cute to pass up.

Both acts were on the three-day bill, which took place at Golden Gate Park this weekend.

Arcade Fire have no other U.S. tour dates on slate for the rest of the year, though they have some stop-offs abroad. The deluxe, 1-year anniversary reissue of their latest album "The Suburbs" dropped earlier this month, details here. The band also dueted with Cyndi Lauper earlier this year, at the New Orleans Jazz Festival.