Open source Video players

Celluloid

Celluloid (formerly GNOME MPV) is a simple GTK+ frontend for mpv. It aims to be easy to use while maintaining high level of configurability. (GPL)

Linux

Dragon Player

Dragon Player is a simple video player for KDE 4. (GPL)

Linux - FreeBSD

MPC-HC

MPC-HC (Media Player Classic Home Cinema) is an extremely light-weight, open source media player for Windows. It supports all common video and audio file formats available for playback. We are 100% spyware free, there are no advertisements or toolbars. (GPL)

Windows

SMPlayer

SMPlayer intends to be a complete front-end for MPlayer. (GPL)

Linux - FreeBSD - Windows - macOS

VideoLAN

VideoLAN (VLC) media player is a highly portable multimedia player for various audio and video formats. (GPL)

Linux - FreeBSD - Windows - macOS

Videos

Videos is a video playback application designed to work with GNOME 3. It's based on Totem, the original GNOME video playback application. (GPL)

Linux - FreeBSD

6 applications