All Asciinema player components are broken in the docs:

This is due to corsproxy.io enforcing users to use a paid plan to use their service. I suggest we look for an alternative, not only for the proxy service, but also for the Asciinema players on the site. We've encountered a lot of issues in the past with this component, and on most corporate networks, it's not working anyway. I suggest we look for a better alternative.