This topic might have a better name.
The Brain of Morbius (in-universe)
Talk about it here.
The Brain of Morbius was a Who video in Earth-33⅓. The Sixth Doctor and Peri Brown were given a copy to review by Doctor Who Magazine which they did using the vid slot on the TARDIS control console. Peri blinked and missed the entire thing, finding that it was shorter on the inside than out. (COMIC: Doctor Who? 113)
Behind the scenes[]
In the real world, The Brain of Morbius was a Fourth Doctor story released on VHS in 1984. None of these details are revealed in Doctor Who?'s narrative, however.