I know what it does when I don't press play: fills my memory with a boatload of bloated interface that has the shittiest navigation of any media player I've ever used. And I still can't just view a list of all series/movies by date.
[EDIT] in fact, now that I think about it, I almost never just browse the catalogue anymore, while I used to a lot. I open it and go to search ASAP, then close it if I didn't find what I want or see something else interesting in the related results. The auto-playing is annoying enough that it's almost totally driven me away from that part of the interface. I knew I didn't like it but hadn't thought about how it'd affected my behavior, but there it is. Time browsing catalogue from "lots" to "nearly none".
[EDIT EDIT] I might add that full-screen ads you have to scroll past (with no indication that's what you need to do) and other general mucking with the plain grid-layout interface make it wicked confusing for my parents. They just got a Roku solely for Netflix and if it keeps doing that I bet they won't use it very much.
On our Roku, if you sit on a movie or show for just a few seconds, Netflix starts auto-playing a video. But it's not the real show anymore, it's a weird custom-Netflix-made background advertisement for the show using random clips set to odd royalty-free stock music that is specifically not from the show/movie you are actually on and doesn't match. It kind of looks like they set some machine learning robot, or some poorly-paid Amazon Turk people, to generate these clips for much of the titles in their library.
Why? Why does this exist? What user testing or data could have happened for Netflix to decide to spend time/money/bandwidth/resources on this?
Not an earth shattering issue or anything. But it's a personal pet peeve to encounter this every time I turn on Netflix. It feels like they are trying to video-clickbait me, even after I've already paid them for everything.
I use the Netflix homepage primarily, rarely searching. I've watched those ads they play and then started watching the TV show/ movie they're for.