How to find your random world seed
I am having trouble getting AMIDST to load a level.dat file.
I finally remembered that it only seems to work on a vanilla minecraft.jar, but it still wouldn't load the level.dat file.
So then I goggled how to find a world's seed, but I only found some online tools that also didn't work.
All you have to do is click Re-Create your world in Minecraft, then you can look at the seed and options under More World Options. Then just cancel and don't recreate the world.
Then you can copy and paste the seed into AMIDST.
To view the world's seed, the player must enter the command /seed .
I read that from the minecraft wiki
By the way, you could use World Downloader mod too, it has same functionality and lets you save a chunk of any world.
Click on the desired world and click 're-create' go to the seed options and the seed will be there.