Plex's media server software has millions of tech-savvy fans, but can it survive the decline of DVDs and downloads? Plex's media server software has millions of tech-savvy fans, but can it survive the decline of DVDs and downloads?For digital media hoarders and pirates, Plex is a household name. The nine-year-old Los Gatos, California, startup makes server software for streaming media files from one device—usually a PC—to phones, tablets, computers, game consoles, and TVs.