I am pretty certain that this is not the first time someone is raising the question.
It's just that I now remembered it again after seeing my latest accepted creative videos.
I have some smooth pans on a tripod that start for example from the sea or a rock to end to a village or a destination on the Ionian islands.
The customer that searches for that destination will only see a thumbnail (I could call it a "dumbnail") that depicts nothing close to that and will naturally choose another one next to it.
The only way to have the thumbnail you want is to shoot still videos, with little action.
Pond 5 allows you to choose beforehand from some selected screenshots.
Shutterstock, after the video is accepted.
Pixta even allows you to choose a still from any second of your video, in 0.5 seconds segments.
I am not an expert on how this feature could be implemented, but I just think we lose a chance of promoting our content,
so it would be something not just welcome but a necessity for Adobe to implement.
After all, if they advertise us properly, we all win!