[1] [CITE@en[Command-Line Interface — Streamlink 1.6.0 documentation]], [TIME[2020-09-30T20:32:48.000Z]], [TIME[2020-10-01T07:47:57.131Z]] <https://streamlink.github.io/cli.html#cmdoption-http-cookie>

[2] [CODE[Cookie:]] や [CODE[--cookie]] と違って1つだけ指定するようです。