First of all: I don't know about that mediaserv, but almost everything you would want to install on the internet tablet are available as ".deb" files. The ".tar.gz" files are _usually_ (with a few exceptions) something else, e.g. packed source archives. Isn't there a .deb file for mediaserv?

EDIT: Went over to the mediaserv thread.. so apparently there isn't a .deb for it. Then the .tar.gz is what you want, but the error message you found sounds like you may have downloaded it in ascii mode. Make sure that you download the file in binary mode.