Hello,
Not sure if this is Samsung specific or not, but thought I would start here since right now I'm only experiencing this on my Samsung smart tv. Random tv shows don't play back smoothly, but I haven't figured out why based on the app or video settings. I say random because it seems to be a growing issue where shows don't have smooth playback only on the Samsung app, even if they have the same video configuration as a show that does have smooth playback. I have provided an example below