Right now, movies can be filtered by “HDR” or “Unplayed”, but not both. I’d request that HDR be moved from its existing location (under “All”) to join with “Genre” and the other second-level filters, OR that it become its own standalone filter.
Similarly, TV Shows should have an HDR filter option.
Note: I have 4K HDR media in a separate library. Not sure if either of these methods work with duplicates (e.g. HDR & SDR versions of a movie in the same library).
You can use an Advanced Filter. The filter can be saved as a Smart Collection that will auto-update as items meet the criteria.
In Plex Web, scroll to the bottom of the list and choose Advanced Filters.
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EDIT: Also, HDR movies sorted by plays. All movies are listed, with unplayed or most played at the top, depending on sort order (choose Plays again to change sort order).
You can find a HDR filter for tv-episodes (it’s not necessarily the entire show that’s available in HDR but individual videos). For some reason it seems to be only available in the advanced filter though.