Léonie,
Thanks to your advice, I could find the 2 videos.

However, I still fail to understand why the smart album return 0 when searching for videos.
If I change the smart album to "animated", I get the same as Library Info:


There are 7 Gigs and 2 MOVs ( which are videos).
So the question is: why does Photo classify those 2 MOV files as animated and doesn't find them as videos ( in smart albums), but still displays them as videos in Library Info ?
Not that it's a big deal. Just a question of coherence and consistency.
P.s.: now looking further those 2 MOV files.


They were shot with an iPhone 8 back in 2021. (Yeah I know I love using old hardware :-D )
It says HEVC.
Maybe it's a live shot that the iPhone has stored as a MOV and Photos has recognised the MOV and therefore as animated (but not as Live Photos). Or maybe Photos considers 2-second shots as animated because it's short.
Do you happen to know the rule by any chance ?