I just double checked, and I was wrong on the timeframe after publication. It's 3 months after, not 1 year, in order to retain statutory relief (fines and attorney's fees).

Also, "publication" is a little more complex. From the US copyright regs:

it is clear that any form of dissemination in which the material object does not change hands, for example, performances or displays on television, is not a publication no matter how many people are exposed to the work.

So, according to the above, if you shoot content and post it on a Web site that you run, it wouldn't be considered publication.

HOWEVER,

when copies or phonorecords are offered for sale or lease to a group of wholesalers, broadcasters, or motion picture theaters, publication does take place if the purpose is further distribution, public performance, or public display.

So if you're a content producer who sells content to webmasters that are going to post the content or sell it, then publication apparently occurs when you license it to the webmaster or wholesaler or reseller.

They should really update this 30 year old interpretation of "Publishing"