A good web article on videocam's light sensitivity can be found here
Basically, the design & build of videocams' chips are often based around the marketability of LUX sensitivity (esp. Sony). Since I do not believe that there is an international standard for light sensitivity for videocams such as ISO/ASA, this term obfuscates the whole issue in marketing-speak. Suffice it to say that the chips are often built for high sensitivity; they are generally tiny; ISO or 'gain' is automatic and often amplified to the point of terrible signal to noise ratios for the sake of a recognisable picture. With automatic gain, automatic shutter speed/frame rate control for low light, tiny sensors and relatively large lenses, it's small wonder that videocams can record in near-dark and have massive focal length ranges. Hope this helps.