The endpoint that provides the storage used is registered by Jetpack plugin, meaning that is not accessible from VideoPress standalone plugin:
Let;s figure out how to fix it. Probably registering a new endpoint in the VideoPress env.
Allow user to upload a poster image from library.
Already supported by https://github.com/Automattic/jetpack/blob/trunk/projects/packages/videopress/src/class-wpcom-rest-api-v2-endpoint-videopress.php#L101
When uploading, we should not store the uploaded video together with loaded videos.
This will allow us to avoid blocking the screen while uploading the video, and the user could navigate across the places while uploading.