Great video editing software that doesn't cost a dime

I haven't been video editing for a while, but recently I found myself looking for a good solution to edit some 1080p with as little quality lost as possible.  Those raw files are either in mp4 format or Flash video format, and right from the beginning I realized that, unlike MPEG1 and MPEG2, there's no real lostless trimming solution, so I started lower my expectation and merely trying to find a solution that can retain quality as much as possible.

At the end I found 2 tools, and both are free:

• Windows Movie Maker
• Avidemux

 I first tried Windows Movie Maker, and while the interface it's simple and easy to use, I found it a bit fragile and I had to constantly save the project in order to preserve my editing work.  But the biggest problem is that it output a video that has different screen size from the original, and that's, to me, unacceptable.

Then I tried Avidmux, and after a bit confused with interface, I managed to edit a video with good precision, and the result was pretty nice.  At first I was confused by the output video not playing properly on my iPad, but later I found out that it's because I didn't choose MP4 Muxer as the container.  So after I used the following setting:

• Video Output: MPEG4 AVC (x264)
• Audio Output: Copy
• Output format: MP4 Muxer

I got my edited video properly rendered and now it plays very well on my iPad.

I did experienced some crashing when I twisted the ending part of my video, but eventually I got things working as the application preserved a crashed project.  But here's my biggest, and properly the only, complain about the application: I have problem finding a way to SAVE the editing project.  I know it sounds crazy, but I did tried saving my project, but I couldn't open it later.  Maybe it's because I did something wrong.  So I will probably spend some time to figure it out.  But at the end, I am still very pleased with the result.