I will not surprise you, but the video quality on the YouTube is also important. Try FLVTO - it works well.
and some are provided by third parties to increase user experience. Here is the best converter https://www.flvto.biz/en74/
I have ever used. It is pretty handy without bags. Simply give it a try. Good luck
Also, there's an opportunity to get our downloader application and desktop version from 2conv.com in case you need more convenient and easy way to get your favorite songs in mp3 or mp4 from YouTube.
By the way, I always use the best online converter because it is important for me to get excellent quality videos. Then I save the frames I need from the video and convert them from jpg to png for further processing. By the way, I recommend you to use this online jpg to png converter https://img-converter.com/en/convert/jpg-to-png/ too, is a handy tool for fast, easy and free conversion