There's a faulty line in the booru.pl script, which causes -s=.. to give errors.
This line seems to reference to the query function in the Booru.pm file (?).
Unfortunately, that's where the script gets complicated. I don't understand the code, and I can't grasp the big picture of the script.
Anyway -s=.. doesn't seem to work, at the moment anyway. This doesn't look like a fault of a recent code change on Danbooru or something (seeing as it has happened earlier, and happens on at least Gelbooru as well).
Anonymous said that removing the use strict; from booru.pl allows the script to run (but not being able to download anything). I still get the same error, whether or not I remove the line.
Might as well add that --pos=.. gives the same results.
In fact, the script doesn't seem to make any sense. The way it's written suggests that the script should download the images in ascending order of ID (smallest ID first), but looking at the output, it seems to start from the highest number...
Actually, I managed to fix the problem. Or rather, I circumvented it. I just basically made a hack which compares the output ID with the maximum ID, so the script starts from the newest files, and goes down to the specified value.
The file: http://ja.pastebin.ca/1624351
If you replace the booru.pl file with this, and it should be usable. Note that I left the -s variable intact. Use -x instead. So -x=55555 will download files from newest, highest post ID, down to post ID 55555.
I know the code is very rough, and I have never done anything with perl before, but it should work anyway. So try it out, and tell if you encounter problems. Right now I need my sleep, though. Badly.
BTW, I guess there's still nothing on the creator of this script?