what video tag can be interesting?
On top of what's available now (v1.0 51) I would say:
- Creation and Modify dates and time, expressed in local time (see below)
- Color depth
- Make and model
- GPS infos
- Media and Movie Time scales
you means the creation_time in movie header?
Yes. See below reminder, how complex it can be but I'm sure you know already.
The standard for metadata in QuickTime includes 3 sets: Media, Movie and Track. Each carries a Creation and a Modify date/time. Ideally all these values are consistent and I would recommend to always keep/make them consistent:
Standard Date-Time fields_EXIF Pro.jpg
Common problems:
1) They are all defined as UTC and no place was allowed to carry the TZ, leaving manufacturers with many options. For example, some camera manufacturers store the local time as they do for picture (old devices and Olympus and still OM Systems). Common workaround is to consider the video as taken in current TZ. Still the question of DST for région where it apply and videos taken in the opposite period (i.e. summer for winter). I think the system may help on calculations. Videos taken during a stay downunder can be discussed later.
2) Generaly speaking, Create an Modify date/time for Media, Movies and Track are identical and reliable as long as the video has not been edited. Here comes the main issue for users as most (~all) video editors (PC, tablets and Smartphones) just replace the original values by the current date/time and sometimes even reset to zéros

It seems Samsung improved recently. I don't know for Apple but it was the case some years ago, even them

The consequences is dramatic in sorting, search, adjust date/time (shift).
Common workaround is to use either the file modification date or a specific field. Hopefully, some camera and phone manufacturers add specific fields to store the local time, sometimes including the TZ but there's no universal standard. For example, some time ago Apple added a field named Creation date (local time including TZ). Canon added DateTimeOriginal, Minolta did something similar. Having a timestamp in the file name helps keeping the original date/time (Samsung and some other smartphones).
managed by thumbnail's label for image, ok?
Yes, keep it as simple as possible. I think of renaming, change date/time, search, filter,... The more the items are consistent between photos and videos the easier for the users. It may need a kind of translation table as well as some calculations in order to play with the challenge mentioned above.
I know, managing the metadatas of videos is quite complex. So far I use command scripts on my PC in order to deal as much automatically as possible with various cases, camera models, file history,... to keep the videos in sync with photos. I would be happy to do the same on.my mobile.
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