Hi all =)
Solved the problem

First i checked the owner of the files, it was set correctly.
The problem was the patch itself, actually its install instructions:
The patch Lobo posted was
1. too old, heres a newer one
http://home.arcor.de/gs-ds/mv_german_hotfix.rar for everyone with the same problem
2. the patch-descriptions were misleading: The new one says that the file has to be copied to /data/tables -> the old one says it has to be copied to /mediavps/data/tables; so i copied the new patch to ./fs2open/mediavps/data/tables and, to be sure, to ~/Apps/freespace2/mediavps/data/tables (folder has to be created)
I gave it a try and

it runs with activated mediavps

Thank you all, you all have done a nice job ^^
Till the next problem

So long,
djmace