Shutter Encoder
Shutter Encoder is a free and open source video converter, image and audio handles tool
Musictube
Musictube is a free and open source program to listen to music/songs from YouTube
MPlayer
MPlayer – free and open source, cross-platform media player
QMPlay2
QMPlay2 – free and open source, multiplatform video and audio player which can play most formats and codecs
Celluloid
Celluloid – free and open source, simple media player that can play virtually all video and audio formats, GTK+ frontend for mpv
SMPlayer
SMPlayer – free and open source media player with built-in codecs, with support for Youtube for Windows and Linux
Selene
Selene – free and open source audio/video converter for converting files to various formats
Kaku
Kaku – free and open source music player supports different online platform like YouTube, SoundCloud, Vimeo and more
Vocal
Vocal – free and open source powerful, beautiful, and simple audio or video podcast client
HandBrake
HandBrake – free and open source multiplatform, multithreaded transcoder converting video from nearly any format to a selection of modern, widely supported codecs