The laws determinning the passage of light through varying densities of transparent material and through varying "acceleration" caused by a common field of gravity have similarities. I prefer to think of warping of the time space continuum as an increase in density. Light bends as it passes from one medium into a denser or into glass, or in the case of the time space continuum, a field of varying density. In the case of light orbitting a black hole, you would simply have to imagine a very huge change in "density", enough to prevent light from leaving. The very center of a black hole is an infinitely small point and the light would still end up orbitting the black hole in some extremely tight orbit. It would also take a long time to travel through the dense field due to time dilation, which is similiar to how light slows down in dense transparent objects. Bearing in mind light cannot gain momentum and if it did have some theoretical momentum (in relation to the displacement it cause when it interacts with a mass) it would take something like 10^50 years to come orbit the center of the black hole and leave out the other end (it's called an event horizon for a reason!). What do you think?