^^^^^^ What he said! I'd recommend training at a boxing gym and getting a good solid foundation in western boxing. Then start going to some of Keith Mazza's seminars (or someone else's) to pick up on some Wing Chun. Or find a friend that does Wing Chun and do some training and exchanging with him. What really counts in any martial art is the "engine"....the biomechanics of how it moves and deals with force. This is what takes awhile to learn well. Second to that is the concepts and strategies the art uses. After that is the actual techniques. But once you have the core biomechanics down well, you can refine the actual techniques used by drawing from any art that is compatible. And you don't necessarily have to study that art from the ground up.
And once you have a good foundation, you CAN learn things from videos. Either DVDs covering Wing Chun or from youtube pages like mine or Paul Rackemann's. The important thing with that though, is have a like-minded partner or partners to work through the material with you.