Ubuntu 12.04 Precise Pangolin
I wanted to make a short clip of a television show available to students, as I thought it would be instructive (a section of QI where the motion of a bullet is discussed). I took a good quality file in flv format and clipped out the bit I wanted, roughly one and a half minute's worth, using Pitivi. This was easy, and the resulting render, again into flv format, was of excellent quality. The file, however, was huge: over 900 MB!
A brief excursion with ffmpeg and avconv was unsuccessful and frustrating, so I tried the media conversion program Transmageddon, which I had noticed in the repository. Two minutes later I had the clip I wanted in a good quality flv file weighing a more useful 22 MB.