Wall Street Journal: It’s still early in the fast-evolving web video world for the likes of BuzzFeed, Vox Media, Vice Media and Mic, but already they’re churning out some “stars” – people whose social media followings and on-camera personas make them employees of some import. Now the name of the game is to hang onto that talent, especially when young people who have built brands for themselves can quickly parlay that into other opportunities.