KPlayer has undergone major changes for the upcoming 0.5 release. There still are some rough edges here and there, but for the most part it already works. Please check it out if you can compile from CVS.
The biggest enhancement is the ability to choose many different settings for individual files, for example you can specify that a file is a playlist, assign a subtitle file to a movie, set additional command line arguments, and so on. The properties you set will be remembered the next time you play the file, even if it have been removed from the playlist.
Some settings will be always remembered automatically, like the subtitle file, subtitle delay and audio delay. Other changes will only be remembered if you make them while holding the Shift key, for example when changing volume, brightness, contrast, and so on. Of course you can change all that through the main Settings dialog. More advanced properties like additional command line parameters, audio and video codecs, using temporary file when playing from KIOSlave, can only be set through the File Properties dialog.
Playing from KIOSlaves is another major enhancement in KPlayer 0.5. For example it allows you to play files over an SSH connection using the fish:// KIOSlave, or play files directly from tar.gz or .zip files using the tar:// and zip:// KIOSlaves, and so on.
Also there is a new little module that allows you to see some technical details of any media file on the Meta Info tab of the File Properties dialog in Konqueror. The information will only be available for files you have already played with KPlayer.
The new message strings for KPlayer 0.5 also already are in the CVS, so now is a good time to translate KPlayer into your language or update an existing translation. See the KPlayer Translation Micro-HOWTO
for details on how to make a translation.