as I mentioned in the reply to this question in the other section you crossposted in, ASIO takes complete control over of the audio signal so you won't be able to hear youtube or other music on the same computer.. like I said I'm fairly sure I managed to override the settings in audio somewhere and allow ASIO to share control but it was a long time ago.. please do try, check your audio settings, there's a checkbox for this and it may work for you
otherwise, do you have another device you can use like an iPod or tablet, or cellphone.. if you can get your youtube vids to play on another device you have a multitude of options.. patch it into the AUX in (sorry, I haven't looked at the inputs/outputs in ages, it may be Line in).. or use an audio interface and patch the feed in there, or buy a small mixer (30/40 bucks or so) then have your pc audio out go into one channel and the youtube playing device in another channel.. be creative, you can do it.. and of course, as the others are suggesting, import your youtube video's audio into a track in your recording software and play along with that.. loads of ways to accomplish it
