Syfy took the unique step of releasing the pilot of the upcoming Caprica series on DVD and iTunes months and months before the show would actually air on television. So it's not particularly surprising that they've gone ahead and released it online weeks before its January 22 premiere. Syfy says they are aware that their could be risk that less people will watch the pilot when it airs as a result. But that was a risk as soon as they released the DVD months in advance.
It looks like they are hoping as many people watch the pilot as possible in any venue, and that even if there is a ratings hit for the pilot, that it will be made up for with viewers excited to see the second episode.
The content will be slightly different from the DVD (I think it has been stripped of nudity, for example) and there will be some previously unseen footage in the TV premiere, which mostly sounds like it is from scenes that were subsequently re-shot and new CGI for some scenes. You can watch via Hulu above, directly on Hulu or on Syfy.com