PyTube is a GUI for many applications like mencoder ,mplayer, ffmpeg, swftools, vorbis-tools, youtube-dl and others.
It allows you to download videos from YouTube and convert them to many formats, it also allows you to convert local video files into other formats such as:

MP4, 3GP, MPG, AVI, OGM, OGG, WAV, MP3, GIF, FLV

You can also merge multiple videos into 1 single avi file, rotate them,
apply a seperate mp3 file into a video, you can generate 10 to 30
seconds ringtone for your cellphone and also re-scale videos.

PyTube requires the medibuntu version of the ffmpeg package