Plex, PlexConnect and OpenPlex are running on Mac OS X 10.10.4 Yosemite beta 1. On April 16, 2015, Apple released Mac OS X 10.10.4 Yosemite beta 1 (build number 14E7f, “pre-release”). I positively tested it with an Apple TV 3 running on Apple TV 7.2 software. Referring to the release notes, the Mac OS X 10.10.4 Yosemite update improves the stability, compatibility, and security of your Mac.
The following set up was used for testing: