A tumblr post of a Twitter screenshot saying "accidentally watched 30 minutes of a breaking bad episode at 1.5x speed didn’t even realize it was like damn these dudes are hauling ass today" and a second reply saying "same but opposite energy" with another Twitter screenshot saying "Better Call Saul is so good that I accidentally paused a scene where Bob Odenkirk was sitting in a chair and I thought it was just a character study of him in silence. I watched a paused screen for 2 minutes and thought it was such great choice."
Watching at 1.5x for 30 minutes without realizing... How high was this person? It's either that, or brain damage; there's really no other explanation.
On YouTube, I change the speed constantly, and, sometimes, I think I'm watch at x1 when I'm actually watching at x1.5 or even x2.
I can usually differentiate x1 from other speeds, but when there's a slow talker and no music, it's actually quite easy not to be able to tell unless I think hard about it, or realistically just check, especially since I'm very used to it, having done that for around two years.
However, watching a show for ~~30~~ 20 minutes without realizing it is unrealistic, especially since there are a lot of sound effects and it's ~~30~~ 20 minutes!