What are the advantages over "asciinema"?
At the moment I only see that it does not require a specific player (javascript for the web), on the other hand it seems you are not able to pause the "execution".
You can view the animation without javascript enabled, and it's media type is image, you don't even need to convert it to base64 to use it. It's like gif but relatively smaller and with more colors, and it's Scalable Vector.
The output is an SVG animation so you can modify it as you want. For example you could add a last frame with the logo of your project.
Not being able to pause the animation is annoying, I will probably add some way to it with ECMAScript in the future.