This is the Software Publisher's description.
Plex is a media platform that is capable of organising your media so that it can be viewed using the Plex app. In addition to allowing you to view all of your music, photos and videos, you can access online content from many of your favorite online providers via Plex channels.
Plex currently supports over 200 channels including CNET, YouTube, Vimeo, Revision3 and many other popular online sources. With Plex Media Server for Mac you can stream additional content from Aperture, iPhoto, and iTunes.