Add Thumbnails in Media Library for videos

It looks like existing videos will not have their thumbnails updated, and it does not seem easy to do this in an update hook, because the Media::updateThumbnail() method is protected. There is an issue about this but it is still in progress: ✨ Expose triggering update of media metadata + thumbnail to end users Needs review .

We need to check that newly added videos also get a thumbnail. So far I only tested with existing videos.

Okay, newly added videos also do get thumbnails. I forgot to switch from source: video_file to source: rokka_video in config/default/media.type.video.yml

@milanbombschliip: there is a post-update hook that should take care of updating the media source. Didn't it work?

@pfrenssen Hmm, now when trying to debug it everything worked fine. The source type got set by the post-update hook and drush cex showed the change and thumbnail picture show up for newly added videos. Not really sure what was going on earlier on my side.

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Thanks for confirming, and for the great contribution! This is an awesome new feature :)