Minitube
Minitube – a simple software for viewing videos from YouTube: just enter the search keyword and Minitube will output an endless video stream
Gnome Twitch
Gnome Twitch – free and open source software allows searching for and watching Twitch streams from the desktop for Linux
Stremio
Stremio – organize and watch videos, movies, TV series and TV channels from different services: Youtube, iTunes, Amazon, Netflix, Twitch and others
VLC
VLC – free and open source cross-platform powerful multimedia player which plays most multimedia formats
Elisa
Elisa – free and open source music player from KDE, that is simple and does not require any configuration when using
Clementine
Clementine – multiplatform free and open source modern music player and library organizer