Sometimes I really love my job. Now and then, I get introduced to a program such as Avidemux that fills a long-standing need. Every video editor I've tried to date absolutely insists on completely re-encoding your video even if all you did was cut or trim. Every single one--until Avidemux. If you're saving to the same type of video, it simply copies all the unedited material to a new file. Talk about a timesaver.
Not only does Avidemux edit, it also re-encodes in a variety of different formats such as MPEG-2 and MPEG-4. It proved quite fast and stable in this regard. The one time I managed to flummox the program into creating a bad file was while joining some previously split avi files. The result was unplayable and crashed Avidemux when I attempted to load it. I was able to repeat the problem, so the joining routine needs some work.
Though Avidemux isn't yet perfect, it's the best video editor and encoder I've run across in terms of overall usability, usefulness, and performance. It's also straightforward and easy to use, assuming a fair knowledge of the process--for free you simply can't beat it. Download it and spread the word.