MTV executive Bill Flanagan helped usher music into the video age and transform VH1 from MTV’s neglected stepchild into a hip pop culture destination. Along the way he created the series “Storytellers” and helped bring in “Behind the Music.” He just published his third novel, Evening’s Empire, set in the venues Flanagan knows best: the private jets, hedonistic afterparties, and ginormous mansions of the rock ‘n’ roll glitterati.