I use software such as RipX, DeMix Pro and such to isolate the guitar and make backing tracks from songs of Rainbow, Deep Purple and Blackmore's Night. I also upload some isolated guitar tracks sometimes.
If you have any question about the software i'm using (RipX and DeMix Pro) feel free to ask and i will answer the best i can. Both softwares are great but the thing that makes RipX stand out is that it has countless of of options and ways to refine and edit the songs which DeMix Pro unfortunately doesn't have. It's a really amazing software and the price for it is relatively cheap as well. DeMix Pro is sadly much more expensive with a montly subscription.
Also here is a link to a website were you can paste the URL of the video and download it to the computer and then use it in Cubase for example or any other software. 320ytmp3.info/
Or search for a YouTube converter on Google.