This extension is excellent. The keyboard shortcuts (which are customizable) are all you need to control it. Speed can be set to what you want and a hotkey can be used to go to a preset speed that you likely use all the time.

However, there is no privacy policy and the extension has the status of 'Access your data for all websites'. This means it can access every on your browser including usernames and password.

Another user has brought issue up; it can be found on GitHub by clicking the 'support URL' on the extensions main page, clicking on 'issues' and then searching for "data". The dev did come back to the user and point that although the extension has "root" access to the browser no information is passed out externally.

All we can can do it take his word for it. A would recommend this information be put into a proper privacy policy which can then be found easier for other user with the same concerns. I'll be looking to find a similar extension that takes privacy a little bit more seriously in the meantime.