actually that is bug which YouTube/Google inc. not allowed in playstore version. But still working in android version 8.x and app version 8.x . But you can convert any youtube video online (no app needed) and download or save to Dropbox directly. In my case after convert, I first save to file to dropbox (within 5 to 10 second file uploaded and saved) and download anytime. https://www.onlinevideoconverter.com/youtube-converter
