VideoSpeed FX от fe2-Nyxar

Video Speed Controller - Firefox Port lets you control the playback speed of HTML5 audio and video directly from Firefox.

You can speed up, slow down, rewind, advance, reset playback speed, and show or hide the on-video controller using keyboard shortcuts. This is useful for lectures, tutorials, podcasts, long videos, online courses, and websites that do not provide good playback speed controls.

This add-on is a Firefox-compatible port based on the open-source Video Speed Controller project. It is adapted from a newer upstream version to provide Firefox users with a maintained and more up-to-date experience.

The extension does not require an account, payment, external service, or additional hardware.