This doesn't mean you have to agree with filesharing, or think it's a good thing, or participate in it, but calling it "theft" is scaremongering.
No, some piracy is not theft. And some is.
Piracy is theft in the sense that it deprives a producer of the income or potential income that they would otherwise make from someone buying a good.
Piracy is like breaking into a warehouse full of unsold toys slated to be destroyed. It's against the law but it's hard to see it impacting a particular person negatively (not that it won't if no one buys toys the following Christmas).
It's conflict between those who believe digital or intellectual property opens up a whole different domain of "property" and those who believe the old rules should apply without change.
I would suggest those arguing for intellectual property not try to equate digital piracy with something like breaking into your neighbor's house and stealing their jewelry. It's a poor analogy. The argument that producers need and deserve to be paid probably carries more weight.
So do successful competitors, boycotts, Internet FUD, and a whole slew of other things, in fairness.
It occurs to me that property (of any sort) is a metaphysical concept.
Also, property is not itself all that metaphysical, at least not if we accept the idea that things actually exist as we perceive them (which seems like the opposite of metaphysics). Some of the trappings we attach to it might be, but property is pretty fundamental to the idea of self. On a very basic level, my property is something I have.