video file icon

• The Finder generates its own icons for video files, which it will show if the Finder View Options have Show Icon Preview selected for that folder (it can be different depending on which folder).
• For video files with meta data, it will show the included artwork. ➔ I prefer this method, for structural and logical use: it is meta data, so add it as such. See below.
• For video files without that meta data, it will auto-select one (early) frame as icon.

These aren't real file icons, but the Finder shows it automatically as icon, unless your settings prevent that.

Aside from the above, you can add ‘any’ image data on the clipboard as icon through the Get Info window - which has been available in some form for decades in macOS and its predecessors. That wouldn’t be fully meta data, so it can only show in Finder on Mac.

➔ “For video files with meta data, it will show the included artwork.”

You may insert artwork meta data through the TV app, or use any of the offered third party apps that let you edit meta data. My app of choice is Subler, as that also lets you add or change text meta data fields, including some fields that the TV app won’t let you edit or add, but some of those fields will show in the TV app if present. Adding artwork can be as easy as drag-and-drop, and then saving the file.

This worked great on my Mac.

Which of the mentioned methods did you use?

When I try to move the video to my iPad, the video transfers fine but the file icon/artwork is missing. Is there a similar method for adding artwork on the iPad?

Embedded meta data artwork will show on iPad, for the Files app (iCloud Drive), as transferred from a Mac.

Embedded meta data artwork will show on iPad, in the TV app (synced video/add to device), as transferred from a Mac.

If you mean editing on the iPad, then I wouldn’t know that.