They were the first musicians to bet big on YouTube. But their approach continues to raise questions about what it means to be a band.

The big one, of course, was “Here It Goes Again,” the one with the treadmills. That song became a hit on the strength of its video, and if you say the words “OK Go” to virtually anyone who ...

(“Here It Goes Again,” a treadmill ballet released in 2006, won a Grammy Award for best short-form video.) OK Go, formed in Chicago in 1998 and now based in Los Angeles, features Tim Nordwind ...