Youtube2mp3 is a cross-platform video downloader and converter that converts YouTube, Google Video, DVDs, and local media files into a wide range of audio and video formats.
YouTuber is an opensource tool created in vb.net 2010 for Windows to download, convert and play videos from YouTube.
AVISmaster is an open-source batch file processing GUI for AviSynth scripts and makeAVIS (which is part of ffdshow). It can generate scripts and .avi dummies with embedded AviSynth wrapper using template for media files located in particular folder.
MPGPatcher is a command line tool to change video basics (resolution/size, framerate, aspect ratio, bitrate) in mpg-video files. Patches the video headers only, does no reencoding.
iBulk is a front-end for FFmpeg used to convert videos for use on an Apple iPod or iPhone. iBulk can be used as a gui or cli. Gtkdialog and FFmpeg with libavcodec and/or libavcodec-extra-* is required.