The real problem with digital downloads—both from a philosophical perspective and a practical one—is that they are not easily graspable as "property" in the same way as a CD, or DVD, or book appears. This gets back to the elusive concept of "rivalrousness" in definitions of property.
Some theorists—too many, in fact—consider rivalrousness the sine qua non of property. Under this view, if something is not rivalrous, it is not "property;" it is merely an inchoate right. But what exactly is "rivalrousness"? Roughly, a "thing" has rivalrousness as a characteristic if using it prevents any other person from simultaneously using it. For example, "my car" is rivalrous: While I'm driving it, my 15-year-old-with-a-learner's-permit isn't simultaneously driving it (fortunately). The wikipedia entry is a good example of the kind of sloppiness in the concept. Have you spotted the fallacy yet? Hint: Consider the reference frame.
In that definition, "rivalrousness" concerns only the perceptions of the potential consumer of the good—the party in an economic transaction that wishes to acquire the thing. The problem is that there is another party in the transaction whose interests have been ignored by the definition: the current owner. For the current owner, each individual purchaser is, in a sense, self-rivalrous: Once the purchaser has the thing,1 that individual purchaser's willingness to acquire the thing has been used up; in a sense, it is self-rivalrous. So, by definition, from the purchaser's perspective anything inchoate is rivalrous; from the seller's perspective, any economic good at all is rivalrous.
Digital downloads are even more complex because there is one party who is both a purchaser and a seller in the ordinary transaction: The recording company, or publisher, or film company. On the one hand, these parties—to avoid confusion, let's call them "distributors"—companies purchase the right to resell "ideas" in a form comprehensible to others; on the other hand, they sell media containing these forms. However, IWTBF2 advocates would bind all distributors to the purchaser viewpoint, find that what they are selling is nonrivalrous, and thereby limit their property rights in what they're selling. And there is the problem: IWTBF ignores the shift in reference frames, and usually compounds the error by conflating rivalrousness with excludability (but that's for another time). It is, in short, a circular argument—and that's not usually a good basis for policy or understanding behavior.
So, then, where does this get us? Probably nowhere. Hopefully, though, it will close off one path through the thicket that definitely leads in circles.