It's called "Runaway Radio" and it's free on TubiTV. 

Here's the description:

"Musicians and DJs from across the U.S. reflect on how radio shaped their lives, and how changes and pressures led to the medium’s demise in the 2000s."

It profiles several different radio stations during the heyday of FM rock, although I'm not entirely sure calling it the medium's "demise" is compeltely accurate. But things definitely aren't like they once used to be.

Still, not a bad near 90 minute movie for no charge. 

Watch it here.