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
SimpleScreenRecorder
SimpleScreenRecorder is a free and open source linux software for created to record (screencasting) programs and games
VokoscreenNG
VokoscreenNG – free and open source is an easy to use screencast software, creator to record educational videos, live recordings of browser, installation, video conferences, etc
Minitube
Minitube – a simple software for viewing videos from YouTube: just enter the search keyword and Minitube will output an endless video stream