It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

I cannot extract most of the titles from the soundtrack archives for The Witcher on my Linux system, neither from, nor from When I try 7z it tells me the compression method is unsupported and unzip complains about bad zipfile offsets.

Any ideas how I could extract the soundtracks on Linux?
This question / problem has been solved by dr.schliemannimage
I downloaded and extracted both files using p7zip on Arch Linux right now, without any issue.
p7zip should extract them without any problem, so I suspect your downloaded files are corrupted.
These are the md5sum data for both files:

Verify them and download them again if needed.

If you still have problems extracting them, try using a different tool such as unzip and check your p7zip installation or usage syntax.
dr.schliemann: Verify them and download them again if needed.
You are right. I already had verified the files against my local checksums, but did not re-download them. And the local checksums also were wrong. Sadly GOG does not provide checksums for their extra files, that would have solved the problem immediately. Thanks!