porn. It gets transcoded enough that the stego could fly through as just another lossy transcoding. Better yet, lossy transcode it to something and back, then stego, as long as your target has a copy of the same transcoder and knows what you're using as reference. You should also be careful to strip metadata as to which transcoder you're using. They're PETABYTES of the stuff floating around.

And if you're willing to pay a few bucks for private cams, there's no way anyone else can have a copy of your screencap, so no amount of clever transcoding will get them a reference copy.