I've heard that a lot of the "cyber-crimes" units are just folks who are running around chat boards and the like, getting the pervs to send them links or naughty pics/videos.
Seems like that's how most of the pervs have been caught of late, that and friends/family/neighbors catching them in the act with the offending material. The fact that until a few years ago the FBI didn't even have the capability of e-mailing outside their bureau tells you a lot.
IOW, if they catch you, you're screwed, but you have to do something pretty screwed up to draw their attention, so it would seem.