Coral's a network of several hundred servers that can store and serve copies of any file on the web. To offer a file via Coral, all you have to do is add .nyud.net:8090 to the host name in its URL.
Here's an example -- the trailer for the underappreciated Brat Pack thriller Bad Influence starring James Spader as a passive yuppie and Rob Lowe as the devil. If Video Detective wanted to save bandwidth and offer the file over Coral, it could change the original URL to a Coralized version.
Coral's also a useful place to look for any URL that can't be loaded due to high traffic or some other problem. Just add .nyud.net:8090 to the host name of a request, as in mp3.example.com.nyud.net:8090/podcast.mp3. There are Coralize bookmarklets for browsers that can request any page from Coral's cache.
The long-term plan for Coral is to expand the network, adding any host who wants to serve requests. This brings up integrity issues raised in the debate over Google Toolbar's autolink feature, as noted by Wes Felter -- there must be a way to ensure that a Coral server is not modifying the original content in transit.
I'm going to see if this module can be fished out of Coral, so I can sign content on Workbench as a testbed for the concept.