What about using a third party recording program like Free Screen Recorder? I've used it before to record individual windows or whole screens and it has a range of different compression tools and codecs you can choose from and a couple of them preserve quality fairly well and dont use up a huge amount of storage either.
I use Camtasia for screen capture, but there are 2 reasons why I don't use it for this:
1) You are actually exporting video that is bigger than your screen, and those screen cappers will only record the portion that is seen.
2) SE hinders rendering to make way for exporting, not the other way around. The result is no skipped frames, and no jumpy playback.
The results I get with exports using DivX encoding/Xvid look pretty good for the most part, and the filesize is more than manageable. I'm really happy with them!
Here's another experiment I did yesterday. I was just trying to get a Terra doing a couple of full rotations, but when I went back to edit the stream I saw that I had been visited by a comet! It was totally amazing, and even though the comet really showcases the artifacts created by the skybox, I still will always treasure this clip because to me it represents how amazing Space Engine is. After literally years of use, I have never been surprised by a comet like that. It flew right by me! I'm so glad I recorded that...
[youtube]fzcQQRz1kLQ[/youtube]