I'm not sure I understand. I just tried the GnuWin32 version of wget in a command tool (~shell):
wget -O ZZZ "
http://localhost:52199/MCWS/v1/Files/Search?Action=mpl&ActiveFile=-1&Zone=-1&ZoneType=ID"
and I get the result in ZZZ without any dialog.
You do need the
-O <filename> option otherwise wget guesses the file name from the requested URL, and it has no clue about non-trivial URLs (wget was designed 20 years ago, and the web has changed a lot since...).
You could also use curl instead of wget, but I don't think the results would be any different.
The dialog you are getting is because you are executing at the command line:
MC20 "/MCWS/v1/Files/Search?Action=mpl&ActiveFile=-1&Zone=-1&ZoneType=ID"
The MC20 command you are executing from the command line does the http request to the 'main' MC20, but the command-line MC20 does not know what to do with the returned file, so it puts up a dialog asking you for the result file location. The 'main' MC20 just acts like a web server, while the command-line MC20 acts like a (fairly dumb) browser.
If you use wget directly, there is no command-line MC 20 in the middle, and no dialog.