[tmf9]

It seems these work by taking the existing iPlayer streams? On the current show "Around the World in 80 Treasures", there was brief snippet of ident and there's a BBC Four DOG on screen.

That is typically how FAST channels work, they give the illusion of being linear channels but really just take the on demand versions and stream them in a linear like way. That's why most FAST channels don't have DOGs or other kinds of graphics unless they're burnt into the programme.