One of the most interesting features of SMPlayer: it remembers the settings of all files you play. So you start to watch a movie but you have to leave... don't worry, when you open that movie again it will resume at the same point you left it, and with the same settings: audio track, subtitles, volume...
Some other interesting features:
Complete preferences dialog, where you can change the key shortcuts, colors and fonts of the subtitles, and many more.
Filters. Many video and audio filters are available: deinterlace, postprocessing, denoise... and even a karaoke filter (voice removal).
Seeking by mouse wheel. You can use your mouse wheel to go forward or backward in the video. The mouse buttons can also be customized.
Video equalizer, allows you to adjust the brightness, contrast, hue, saturation and gamma of the video image.
Multiple speed playback. You can play at 2X, 4X... and even in slow motion.
Audio and subtitles delay adjustment. Allows you to sync audio and subtitles.
Advanced options, such as selecting a demuxer or video & audio codecs.
Possibility to search and download subtitles from opensubtitles.org.
It can play Youtube videos. A Youtube browser is included, which allows to easily download Youtube videos too.
Translations: currently SMPlayer is translated into more than 30 languages, including Spanish, German, French, Italian, Russian, Chinese, Japanese....
Possibility to change the style and icon set of the interface.
Free and opensource. SMPlayer is under the GPL license.
Install SMPlayer ubuntu
Open the terminal and run the following comamnds
sudo add-apt-repository ppa:rvm/smplayer
sudo apt-get update
sudo apt-get install smplayer smtube smplayer-themes