Meeting recording auto-expiration feature is no joy.
The Problem
As part of the devolution of the new Stream built on SharePoint, new recordings automatically expire 60 days after they are recorded.
This means that team meeting recordings shared by other people will be deleted in 60 days (they are view-only and cannot be downloaded).
The Solution
Download the file from the service URL.
Open Firefox (or the browser of your choice) and load the SharePoint page with the video that you want to download, then open the page inspector (Ctrl + Shift + C). Click on the Network tab. Type videomanifest where it says “Filter URLs“. Press F5 to refresh the page. When the page reloads, copy the file URL. See below.
Use ffmpeg to download the video by pasting the URL from above:
$ ffmpeg -i "https://copied_videomanifest_url" -codec copy video.mp4