A new article in the Guardian describes how the one of Britain's intelligence collects Yahoo webcam chats of individuals not suspected of any crime. The extent of the survelliance is pretty scary. You should read the whole article:
http://www.theguardian.com/world/2014/feb/27/gchq-nsa-webcam-images-internet-yahoo
Given the whole scary 1984esque mass surveilliance, there is one funny part:
Sexually explicit webcam material proved to be a particular problem for GCHQ, as one document delicately put it: "Unfortunately … it would appear that a surprising number of people use webcam conversations to show intimate parts of their body to the other person. Also, the fact that the Yahoo software allows more than one person to view a webcam stream without necessarily sending a reciprocal stream means that it appears sometimes to be used for broadcasting pornography."
The document estimates that between 3% and 11% of the Yahoo webcam imagery harvested by GCHQ contains "undesirable nudity". Discussing efforts to make the interface "safer to use", it noted that current "naïve" pornography detectors assessed the amount of flesh in any given shot, and so attracted lots of false positives by incorrectly tagging shots of people's faces as pornography.