Start a clean level with the start button and never use the R-Key to restart the recording because that results in a mix with the previous bad demo. (Megaplex bug.)
After you finished playing and reached the Exit properly, wait some time (10 seconds or more to be sure) and do nothing at all. (Original Megaplex bug, maybe already repaired in your version. I don't know.)
Then choose from the pull down menu File/Save as... and choose a directory, save as ".SP" and a proper file name. That is all. Sometimes you cannot choose that ".SP", so then save as ".MPX", which is exactly the same but with 20 extra bytes at the beginning. (These 20 bytes define the level size and some more.)
It is important to know the directory, because if you don't look which directory is active, you may never find the recording. If you took the level from a different directory as you used before, the recording will not be in that new directory but in one of the old ones, so look carefully where you save your recording.
I tried this and still nothing.. it is so weird.. I open a level then press spacebar to start the level. I finish the level (or die). Then I wait for a couple time and go to save file as.. then i change the name to SOL or something like that. Then I press save and the level comes up again with no demo :S
Last edited by Aron Langerak; 08-02-2011 at 12:02 PM.
Can you send me such a "SOL"? Maybe from that I can see what is wrong.
Do not save more than once, because that may indeed strip the demo from the level.
(If you did as I described, and the recording is indeed only 1536 bytes long, you may need to reinstall Megaplex.)