Hi John and Yavor,
This now really was an instructive and informative video. Finally I get Fiddler to cooperate with my localhost and/or the development server on any desired port.
A a result of this I think I was able to find out why my service was not responding to requests. Fiddler says:
No Proxy-Authenticate Header is present
No WWW-Authenticate Header is present.
So far so good, but WTH do I do to get rid of that?