Err...maybe I am side tracking here, but how does YouTube filter adult content, i.e. remove uploaded videos or prevent uploading of videos that have adult (or blatant porn) content?

I figure if someone complained about a video, sure, youtube admin would check and then remove it.

However, at the point of upload or shortly after, is there a way to filter or screen the video content for adult material (e.g. with a script of some sort of software program) ? Short of having a human reviewer look over each and every video as a content filter that is, which just doesn't seem practical or cost-effective.

Along the same lines, I wonder how it would be possible for YouTube to check for copyrighted material in each and every uploaded video WITHOUT a human reviewer?

Of course, "impractical" or "not cost effective" will not be a good defense in court, I suppose