Q: How to download a video from a HTML video element when the "save as" menu item is disabled?
A: Usually the "save as" menu item is disabled due to streaming, often in m3u8 format.
Start the video with devtools open and look for requests for an .m3u8 file, then run this command:
ffmpeg -headers "Referer: https://some-website.com/" -i "https://url-to-m3u8-file" -c copy output.mp4