As of June 10th, 2020 – you can only embed Twitch content on your site if you are using https:// with a valid SSL certificate.
The statement from Twitch, found here.
With this new configuration, Twitch embeds can only be embedded on https sites. Non-https sites should plan accordingly if they intend on continued use of any Twitch embed experiences that are currently in operation on their site.
From Twitch: Any third-party site or developer currently using embedded Twitch features (chat, video, and everything).
This affects every one of the StreamWeasels themes and plugins. So if you intend to use any of our products, you should plan on acquiring an SSL certificate for your website.
The easy way would be to get in touch with your hosting provider and have them setup and configure an SSL certificate for your site. Your hosting provider will likely have a one-off or yearly charge for this.
If you’re more technical, SSL certificates are available for free these days from various sources. We would recommend Cloudflare, which is a free CDN you can configure for your website.