Xt7-Player is a graphical user interface for Mplayer with a huge list of features, "while trying to keep usability in mind". Among the most important features are YouTube and Shoutcast integration, dvbt, library and playlist management, local and global hotkeys, "stackable" Audio and video filters managed via drag'n drop, audio and video equalizers and lots more.
It can even watch your /tmp folder for Flash videos and play them (like a tweak we've posted a while back, but fully automated).
At first, I was a bit skeptical because Xt7 Player is written in Gambas / Qt (I was influenced by other applications written in Gambas which don't look too pretty), but I've decided to give it a try after reading a lot of positive comments on its forum. And I must say, I was impressed! Yes, it doesn't integrate too well in GNOME, but it has all the features (and can play most video formats since it uses mplayer) I want and of course, it's fully customizable: you can easily move the tabs from top to left or show/hide the left panel with a click and so on.
Here are a few more Xt7 Player screenshots:
More screenshots (under KDE) here.
Xt7-Player is available in a PPA for Ubuntu 12.04, 11.10, 11.04, 10.10 and 10.04 users.
To install Xt7 Player in Ubuntu, use the commands below (the first PPA is required for the latest Gambas 3):
sudo add-apt-repository ppa:nemh/gambas3 sudo add-apt-repository ppa:eloaders/xt7-player sudo apt-get update sudo apt-get install xt7-player
The YouTube integration depends on YouTube-dl, which is outdated in older Ubuntu versions but you can download the latest youtube-dl .deb from HERE.
Arch Linux users can install the latest Xt7-Player via AUR.
For other Linux distributions, get Xt7-Player from HERE (note: the latest Gambas 3 is required).
Last (KDE) screenshot in the post via Xt7-Player forums.