I believe that this is a software problem with D-Link. My webcam used to work fine, but just recently I only get as far as the spinning icon with the cation “Loading mydlink function...” but it never finishes, in spite of the fact that the camera icon shows with a green checkmark. Also, I CAN access the webcam using the DLink app on my iPhone. I have NOT changed to the new Mac system software yet, so one cannot say that Mountain Lion is the problem.
A correspondent of mine reports that all his D-Link webcams are also suddenly unreachable.
Conclusion: this is DLink software problem. I suspect that their software is a bit goofy. A good temporary solution for DLink is to undo whatever they recently did to cause the problem, and send their programers back to the coding room to do things right next time. Ands this time, TEST the code before putting it into general use.