Twitch streams can't be watched.

[raphipod]

In the most recent version, 2020.03.01, Twitch playback won't work:
Error-Code: 1000

[raphipod]

It won't ever work. Twitch still uses Flash, which isn't supported in CefSharp anymore.
Twitch said they were going to switch to HTML5 in 2015 already, but nothing is seen.
Sorry.

[amaitland]

You can still use flash until such time as chrome removes support. Flash is deprecated and disabled by default. It is possible to enable flash and use the system wide flash installer to use flash.

https://github.com/cefsharp/CefSharp/wiki/General-Usage#adobe-flash-player-pepper-flash