Column symbol causes --ytdl-raw-options=proxy="socks5://127.0.0.1:9999/" to fail?

[engineeror]

--ytdl-raw-options=proxy="socks5://127.0.0.1:9999/" fails via shell and SMPlayer:

$ mpv --ytdl-raw-options=proxy="socks5://127.0.0.1:9999/"
Expected '=' and a value.
Error parsing option ytdl-raw-options (option parameter could not be parsed)
Setting commandline option --ytdl-raw-options=proxy=socks5://127.0.0.1:9999/ failed.

Exiting... (Fatal error)

Column symbol seems to be the cause:

$ mpv --ytdl-raw-options=proxy="socks5//127.0.0.19999/"
mpv 0.27.0 (C) 2000-2017 mpv/MPlayer/mplayer2 projects
 built on Wed Sep 13 10:50:48 CEST 2017
ffmpeg library versions:
   libavutil       55.58.100
   libavcodec      57.89.100
   libavformat     57.71.100
   libswscale      4.6.100
   libavfilter     6.82.100
   libswresample   2.7.100
ffmpeg version: 3.3.4

Usage:   mpv [options] [url|path/]filename

Basic options:
 --start=<time>    seek to given (percent, seconds, or hh:mm:ss) position
 --no-audio        do not play sound
 --no-video        do not play video
 --fs              fullscreen playback
 --sub-file=<file> specify subtitle file to use
 --playlist=<file> specify playlist file

 --list-options    list all mpv options
 --h=<string>      print options which contain the given string in their name

It parses the option just fine but that's not a valid URL. Any hints please?

[engineeror]

wrong git sorry