"Digital Copy" is separate from "Ultraviolet". The Digital Copy has two different formats. The most common being a code in the sleeve that you enter online, and then download the movie. The time limit with regard to "Digital Copy" is not for usage, but for download. You simply need to do it right away when you buy the movie. Then it's in your iTunes on your computer. I think you've actually got like a year or something. The other (less common) form of digital copy is an extra disc included with the movie which you load into your iTunes through your disc drive. Same effect, but there's no expiration date; and I think you can do it over again if you ever lose the data or get a new computer. Ultraviolet on the other hand is an online account which allows you to stream movies that you've purchased. I suppose it's handy for people using more peripheral devices such as phones or iPads, but I've no use for it. I actually want my copy, and the DVD/Blu-ray/Digital Copy is quite simply the best. For approximately $5.00 more than the DVD; I get to have it on my computer, the Blu-ray, and the DVD.
No matter where you go, there you are.