Like it or not, Youtube is now the No.1 place the majority of music listens go to, to listen to musical content.
There are pros and cons, as with everything in life.
The major stumbling block for musicians is the remuneration for song plays. You need 600 or so song plays to equal 1 download! (Don’t quote me on the figures, just a quick head calc, do the math yourself to see how bad it is!).
But, that being said, if you can catch the Youtube viewers eye there is the potential of many, many, many, many (get the idea!) more plays than could possibly be achieved by downloads alone. So it shouldn't be discounted.
Again, don't quote me on this, but I think you need a tie in with a collection agency like Rumblefish who operate with major content handlers like CD Baby.
CD Baby have written several guides to monetizing your music via Youtube, here is the most recent.
Complete link if the above doesn't work. Have fun.
http://members.cdbaby.com/campaigns/request-youtube-guide.aspx?Source=YOUTUBEPAGE-YOUTUBE-MEMWEB&Dest=https://www.pages04.net/discmakers-cdbaby/CDBabyProspects_MASTER/YouTube_Guide