What problem does this address?

The feature to embed a video from a URL is now available in the Gutenberg plugin via this PR #73023 and appears to be on track for inclusion in the 7.0 core release.

Currently website or multi-site owners can prevent editors from adding background videos to their cover blocks by not allowing video file type uploads. However, this change will open up background video use for the cover block via a URL to everyone which has branding and accessibility implications (See this related accessibility issue: #38975 about adding video controls).

What is your proposed solution?

Add an option to opt out of the " embed a video from a URL" feature for the cover with theme.json or a filter.