Thumbinals and images for video updates shuld be replaceable

Dear Developers,

You may have noticed this

That means when ever a video is private there is no chance to get a thumbnail for a video when it is marked as private on the video providers platform . Below there is an example with some vimeo videos There is a similar behavior on YouTube

If it is not possible to fix the bug i mentioned (may be it is the wrong one) perhaps there is a way to replace the entries for the thumbnails so that users are able to upload and replace them manually.

Panoply has already done that so it should not be that hard to make this feature aviable.