With most of the major streaming video services now accounted for, Google needs to look elsewhere to expand its family of Chromecast-compatible apps. Today the company took a big step in that effort, announcing Chromecast support for 10 third-party apps including Vevo and Songza. Google is also paying some attention to advanced users; Plex, an app thats hugely popular among home-theater enthusiasts, has also gained Chromecast support.