And now, the video of the performance is online. Both bands joined to create Imagine REO SpeedDragons, performing REO's classic hit "Roll with the Changes"--perhaps relevant for fans of either band viewing such a strange, unexpected pairing.

But it worked. The performance was, understandably, most in the vein of REO's original, but Imagine Dragons added their signature bombastic percussion and kettle drums at the beginning, while frontman Dan Reynolds supplied the vocal on the second verse, sounding slightly more uninhibited than he generally does on his own band's songs.