Intruders have entered the world of video. They're small, they're stealthy, and they offer the biggest bang for the buck since the Alaska Purchase. We're talking, of course, about digital SLRs—specifically those that shoot high-definition, progressive video. These hybrid interlopers, called VSLRs (or HDSLRs), are wielding their swollen sensors and 35mm optics like digital clubs over the heads of prosumer video enthusiasts. Each new model seems to pry another finger loose from the once-secure grip of affordable HD camcorders.