Here in the US, it is perfectly legal for you to listen and "download" the satellite data. Since the data is created by a public agency, it is considered to be in the public domain and not subject to copyright. On this website at http://www.weather.gov/disclaimer, you can find the following:
"The information on National Weather Service (NWS) Web pages are in the public domain, unless specifically noted otherwise, and may be used without charge for any lawful purpose so long as you do not: 1) claim it is your own (e.g., by claiming copyright for NWS information -- see below), 2) use it in a manner that implies an endorsement or affiliation with NOAA/NWS, or 3) modify its content and then present it as official government material. You also cannot present information of your own in a way that makes it appear to be official government information."
There's a lot more information there that you should read. I am not a lawyer, but I would assume that with the information being in the public domain and with Germany being a Berne Convention signatory, you should be just fine.
You might want to contact your country's copyright office and make sure, but I use the weather fax as transmitted on HF all the time here.