Issues with embedding from RSS

I don’t understand why I’m on the embed page at all.
The complete feed URL is already input.
Can’t the plugin slice and dice the URL into Allowed Hosts and Path Whitelist without my inputing it all twice?

The example input on the RSS Polling plugin and the Embed page don’t correlate.
‘feeds’ is a subdomain on one … then later a path?

I’ve been trying with a few RSS feeds.
This one … BBC Health - BBC Health - Admin user

allowed hosts - feeds.bbci.co.uk
path whitelist - /health/.*
into a Health category

I think the above should work, but it doesn’t.
I’ve tried every possible combination for hours now.