Anything with motion. Sports, games, vlogs, and so on experience immense improvements. And it's not like it takes 2x the bandwidth, because inter-frame compression can be smarter about it. It's like 30-50% more bandwidth.

Gaming footage/videos, some games are so fast they are noticeably better to play at (and watch at) 60fps over 30fps.

I'd personally rather watch 480p60 than 1080p30. There's a lot of material in which spatial resolution is mostly irrelevant (e.g. presentations, which involve people talking and slides designed to be legible from a distance), but low framerate always looks unnatural and distracting, even after speeding it up by 1.75x or 2x. 60fps should be considered a bare minimum, not "high framerate".

Sports is a good use of HFR. Sadly, when HD broadcast came out, most broadcasters choose 1080i59.4 to remain compatible with the interlaced HD CRTs that were around. One of them chose 720p60 for sports. As cool as HD was, it still had interlacing as a boat anchor chained to it. 4K finally saw the elimination of interlacing, but that's veering way off topic.

For talking head/creator type of stuff, 24fps is probably wasted and could be just fine at 12/15fps.

I'll take 60 over 30 any day of the week, assuming the original was mastered that way (interpolation is fake and bad). Even for just talking head videos, 60 looks better to my eyes. The lower frame rate of films and most other content looking better seems to be nothing but a (sub)conscious 'that's the way it should look' attitude to me.

Oftentimes it's not that big of a difference in size, especially with modern video encoding like av1. There are many cases where higher frame rate improves viewing experience, like smooth motion (smooth movements of something, like people or things, panning, etc), heavy motion (when it's just more intense), giving the eye a little bit more to hang onto.

One particular great use case is dance choreography, so that's music, music videos, dancing videos, quite a chunk of videos and viewership. Most of music videos are gonna be released in 24 fps (a few 30 fps here and there), but there's a lot of "extra content" (tv shows, performances, live recordings, etc.) released in 60 fps, and there's some demand for higher frame rate like 60 fps (seeing from uploads of interpolated videos). 30 fps can be enough to have some smoothness to it, but at 24 fps it can become more jarring if not just noticeably choppy, sometimes 24 fps video is just not particularly great to look at in terms of literally just seeing and discerning what's going on. Sometimes things can end up looking choppy (like in daylight, at faster shutter speed, etc), or have more pronounced motion blur (which is good and better for motion continuity, but at 24 fps it can be a bit much). Motion continuity is quite important, and sometimes even made up frames from interpolation can improve viewing experience, even at a cost of some interpolation artifacts, when the end result of smoother motion is more pleasant to look at.

Of course, it can be a case of experiencing something better and then seeing things as choppy looking back (and 24 fps can really look choppy in immediate comparison), and it may not make that much of a difference if you've just been mostly seeing 24 fps video and not thinking much of it, or seeing 30 fps which is smooth enough. But in my opinion, even starting at 40-48 fps, that's already gonna feel much easier for the eyes compared to 24 fps. Sometimes there's just a bit much going on in the frame and 24 fps is not enough. Our eyes don't see in 24 fps after all. (also, higher frame rate doesn't preclude from using cinematic techniques, including motion blur and all)

How much extra bandwidth does it even take to double the framerate? The frames should be highly correlated and as long as you only add p-frames, the data needed should be pretty small, no?

>Are there specific cases where "HFR" videos are really improving the viewing experience of particular (types of) content?

Yes. Every single one. It's that simple.

Any cases are like that because it looks more natural and fluid, but it's just not for you, though in that case how would cases help change your stylistic preferences?

I mean, even for the obvious highly dynamic videos like some sports and video games it's not like you can't enjoy the bad old 24fps people have been enjoying for decades

> monthly (mobile) data caps

Are we back in the early 2000s or something?