Nielson Research in years past would ask volunteers to attach special equipment to their televisions to report back what they were watching, and for how long.

Nielson Research in years past would ask volunteers to attach special equipment to their televisions to report back what they were watching, and for how long. Even nowadays, I have a relative that carries an always-listening device to track ambient music being played/heard. A technology like this would make it easier to run a program with a subset of volunteers online, w/o them needing any special equipment. Of course, given that slightly more people (than tech communities) are aware of the dangers of an uncovered camera, the possibility of using this broadly w/o consent is nearly nil.