In the time I've been researching Slow TV, I've seen it referred to as:
Wallpaper TV: Something which is always 'there' while you're in the same place as it (obviously). The same kind of effect as a good screensaver which can be a pleasing distraction for a short while. I don't like this alternative so much as it links up with ideas of hanging wallpaper, or something to look at while you're bored. Which of course it can be, but it can be (and largely is) something to watch because you want to, not just happen to be looking at because you're not passively staring at something else.
Temazepam TV: Referring to the drug-like hypnotic and calming effects which some have encountered while watching it. Positive in linking to good effects, not so positive in associating with a drug which makes you sleep. While Slow TV can be calming, it is more about staying in a relaxed, aware and awake state. Seems to have been first used here by Time Magazine in July 2013 - but not the first time it has been likened to a drug.
Valium TV: By sociologist Trond Blindheim - here at Dagbladet in June 2011, in response the Hurtigruten Minutt for Minutt becoming a national event. It's not the first time TV has been referred to as a drug - The Disposable Heroes of Hiphoprisy had a track in 1992 called "Television - The Drug of the Nation". Video worth watching.
Telescargot: A contraction of the French words 'Tele' and 'escargot' - meaning TV and snail, respectively. Would translate as "Snail TV" - which works as a phrase to apply to Slow TV.
Ambient TV: The best fit phrase for Slow TV, one could argue. Like ambient music, it could be watched actively, enjoying the nuances of the images which come your way, or kept on in the background continually, returned to when interest dictates. An augmentation to whatever mood or aesthetic the viewer chooses. It could be immersive or superficial, by choice or by the underlying frame of mind in which a viewer encounters it.
Slow Television -The Slow TV Blog