reEmbed - Custom YouTube Video Player

Sayonara Player - Sayonara is a simple but nice audio player and holds a lot of features like a library, id3 tag...

TabFloater - Browser extension to use picture-in-picture with any website

Pi MusicBox - Pi MusicBox is a great music platform where you can create songs and is the only streaming music player for Spotify, Google Music, Podcasts, SoundCloud, Webradio, and others.

Vid Repeat - Loop YouTube videos for X minutes or for X times. Loop a full video, or only a selected part, add a delay between the loops, and share the loop with your friends.

GNOME Music - Music is the new GNOME music playing application.