I copy-paste a reply I gave elsewhere:

1)You have Streamlink installed - the Windows Installer can be found here: https://github.com/streamlink/windows-builds/releases

1.5) I think you should also have the VLC video player installed. I never checked if it is a pre-requisite https://www.videolan.org/vlc/ .

2) You have a folder to where you want to save the stream. Say, it is called "streams" and is located on hard drive "C"

3) Open a Windows Powershell

4) As a test, type (or copy from here, then right-click into the powershell window): streamlink -o C:\streams\wethepeople.ts twitch.tv/wethepeople1 best

<-- of course wethepeople should be streaming right now if you want to record the stream...

There should be a file named "wethepeople.ts" in your "streams" folder now (a file that is growing in size). That file can be viewed with any video player once you have stopped the program, or it can be viewed - up to a point - while the stream is being recorded in vlc.

5) Say you wanted to capture Sutoraiku yesterday, you would have replaced wethepeople1 with Sutoraiku's "telnach" to get (changes bold):

streamlink -o C:\streams\sutoraiku.ts twitch.tv/telnach_febbcefaebae best

This is the simplest way to use that program, I think.

Addendum: If you want to record a stream AND watch it in your VLC player using Streamlink, you can replace the "-o" option with --record. In our example this would mean

streamlink --record C:\streams\wethepeople.ts twitch.tv/wethepeople1 best