We should improve the display of legacy media (without imeta tags)

This one is a good example: https://gleasonator.dev/@fascinating@nostrplebs.com/posts/fddfe0b52fee7f537f9119154b05d194fc22bde3e5a93b1256cdfbaaa30336ad

Problems with it:

• The video URL is in the text of the post itself. (fixed by !717 (merged))
• The video is letterboxed.

This happens because the client that posted it didn't add any imeta tags.