* No, that's not entirely true. I don't have to use a service like thepiratebay.org to send one of these files. And further, I could just as easily use _any_ or _many_ trackers inside my torrent. *
Altered to convey another point. Naturally, it would be quite difficult to "embed" a feature length movie into a single url, but if one was to split the file into chunks like torrent transferring does, or simply a multi-part rar like newsgroups still do, it enables each chunk to be more manageable.
I do agree with you though, but I think the reason that a service like this if changed in such a way to be user-friendly for file sharing, not just document sharing, would be able to get around a lot of the pitfalls a torrent tracker (for example) would have if it's DNS lookup was blocked (which aren't many) is due to the simple fact that SOPA is written in a way that assumes all IP addresses and DNS names are statically tied together and slow to alter, not that I can have a new domain name in a matter of minutes that resolves to my existing server. Even more so if the final URL hash was nothing more than a common and known algorithm, like base64, that one could easily plug into a basic desktop app and get the same result.