Screen record and crop then put into CapCut then you do your edit
Or use a mp4 downloader then save to files on your phone or whatever and then import into capcut
Try this website
https://ssyoutube.com/en140yN/youtube-video-downloader
Or literally just type "pp" after the YouTube URL, so it looks like this:
www.youtubepp.com/
Screen record and crop then put into CapCut then you do your edit