Maybe it's just that I'm an A/V dork but the idea of a malevolent entity living within television signals in the 1950s is cool as hell and the episode uses the concept about as well as you could hope, with a very good creepy TV host performance from Maureen Lipman. She chews the scenery just the right amount and gets the best lines, naturally. "Are you sitting comfortably? Good. Then we'll begin."
The story is chock-full of surreal, nightmarish imagery that's very effective, and the whole thing feels like the kind of entity and event you might find in a good SCP article.
It also competes with Thor (2011) for Most Dutch Angles In Anything.