SMPlayer is a media player with built-in codecs and support for Youtube.
SMPlayer supports the most known formats and codecs: avi, mp4, mkv, mpeg, mov, divx, h.264... you can play all of them, thanks to its built-in codecs. You don't need to find and install third party codecs.
SMPlayer can play YouTube videos and it's also available an optional plugin to search for YouTube videos.
SMPlayer comes with several skins and icon themes, so you can easily change the look of the player.
SMPlayer can search and download subtitles from opensubtitles.org.
SMPlayer includes many advanced features like video and audio filters, change of the playback speed, adjustment of audio and subtitles delay, video equalizer... and many more.