Paul, unfortunately I don’t know of any web sites that teach this kind of information. The truth is that vetbal descriptions are worthless and visual demonstrations are only semi-helpful. This is something you really have to feel to learn. Therefore, you really need to find a Wing Chun or JKD instructor to learn sticky hands, and these guys are far and few between. Other martial arts such as Aikido, Tai Chi and Kali also use sensitivity drills, but again, you have to learn by doing, not just seeing. And as Coach Davies pointed out, these drills have to be specially adapted to football. However, if you want to begin to understand the basic concepts of sensitivity drills, I would recommend the following books: “Entering to Trapping to Grappling” by Larry Hartsell, and “Jun Fan/JKD the Textbook” by Tim Tacket and Chris Kent.