A Chromium/Firefox extension to download videos from Scratch using the MediaRecorder API.
On Microsoft Edge Store, Chrome, and Firefox
https://microsoftedge.microsoft.com/addons/detail/modhjbffcgblcgnpnleopffhljghghcf
https://chrome.google.com/webstore/detail/scratch-downloader/ceeackimohhoibchhooifgikfibjfmmk
https://addons.mozilla.org/en-US/firefox/addon/scratch-downloader/