No, don't add the feed, "click Download". subscribe.getmiro.com always gives 404, you can see the error message when you visit the page from a browser. Miro just gives "http error". I am not talking about adding the feed *facepalm*
I also have the same problem. The curious thing is that sometimes (I don't know why) it works. However, this case is rather seldom. I took a look on the protocol and it seems that the youtube server replies with a HTTP 403 Forbidden.