[kilian]

This is strongly in tin-foil hat territory but: streaming video costs a lot more money than streaming some JSON to populate a UI. Every minute you spent browsing the catalogue over playing a video is probably a significant costs saving for Netflix.

[Cthulhu_]

At this stage the cost is probably more in licensing fees and production costs than data streaming though.

[nottorp]

But they play those previews automatically... and that's still bandwidth used.

[tonightstoast]

And tragically most users prefer the auto playing previews. Theprimeagean has a YouTube video about how he tried to a/b test it before release thinking "no way that's what users would prefer" and was unfortunately wrong.

[kilian]

A short, compressed, small video that's edge-cached beats always out a 4K stream, so it even works as a tactic to keep you in that overview longer.