Here is solution:
https://trac.videolan.org/vlc/ticket/6244
Working command line argument:
set url=http://nimlive1.giniko.com/bbcworldnews/bbcworld/playlist.m3u8?wmsAuthSign=c2VydmVyX3RpbWU9OC8xLzIw MTcgOToyNToxMyBQTSZoYXNoX3ZhbHVlPTJUSjUzenlPNkRyRW tJMFovU1F4TVE9PSZ2YWxpZG1pbnV0ZXM9MTQ0MA==
vlc.exe %url% :http-user-agent=Mozilla/5.0
urlsnooper does not show any user agent, Giniko stream plays, user agent passed "as a per input option".
Logging can be set in this way, reading log file didn't help.
--extraintf=http:logger --verbose=2 --file-logging --logfile=c:\vlc-log.txt
Whenever possible use ffplay.exe. VLC is CPU resources hog.