gst-av is a GStreamer plug-in that provides support for libav (a fork of FFmpeg). It is similar to gst-ffmpeg, but all libav codecs are supported, even if there are native GStreamer alternatives, including VP8, MP3, Ogg/Vorbis, and AAC.
Medusa is a music player which features a simple interface, easy tag editing, drag-and-drop from the file manager, moving files to the trash folder, moving files to a particular folder, remembering the last five folders, desktop notifications, and Last.fm support.
Webcamoid is a webcam plasmoid for the KDE desktop environment and based on GStreamer. It allows you to take pictures and record videos, and manage multiple webcams with custom controls for each webcam. It also provides some funny effects.