> When I am getting any *.tgz, I can see "shell" of
> tgz, inside of that something (*.tar usually) exist.
> And real content is inside this *.tar.


Yep - the server is incorrectly advertising a "Content-Encoding: x-gzip"
header, which imply that the file is actually compressed *by the server* and
not *per se*.

Added a hack for this case:
<https://code.google.com/p/httrack/source/detail?r=1223>