You must first add a repository, before you can install plexhometheater: 
sudo add-apt-repository 'ppa:plexapp/plexht' && sudo apt-get update && sudo apt-get install plexhometheater
You must first install plexmediaserver from 
https://plex.tv/downloads for your Distribution, before you can build plexmediaserver. At time no ppa repository available 
You must first add a ppa repository before you can install spotify: 
sudo add-apt-repository 'deb 
http://repository.spotify.com/ stable non-free' && sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 94558F59 && sudo apt-get update
You must first add a ppa repository before you can install ffmpeg: 
sudo add-apt-repository ppa:samrog131/ppa && sudo apt-get update
You must first add a ppa repository before you can install ffmpeg: 
sudo add-apt-repository ppa:samrog131/ppa && sudo apt-get update
You must first add a repository, before you can install xbmc: 
sudo add-apt-repository 'deb 
http://archive.mene.za.net/raspbian wheezy contrib' && sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key 5243CDED && sudo apt-get update