AnnotationsReloaded is a Firefox extension that uses YouTube's code to display annotations if they are available from omarroth's archive. It works by replacing the contents of network requests for annotations with their archived versions when they are available. Please note that the code for rendering annotations may be removed from YouTube at any time. Because of this, afrmtbl and others are working to reimplement annotations using new code, and contributors are always welcome. If you have saved annotation XML files from before the annotations removal on January 15, 2019, please submit them to omarroth so they can be included in the archive.
This extension is currently unavailable for Chromium-based browsers (Chrome, Opera, Vivaldi, Brave, etc.) because Chromium extensions cannot modify the bodies of web responses.
Download AnnotationsReloaded for Firefox
Or view the addon on AMO.