[rollcat]

You don't need the "secret" feed link.

You can visit a channel's page directly, and copy the normal URL straight into your feed reader. It will do the right thing - thanks to the <link> tag, which YouTube advertises in the page source - as recommended by TFA. Your feed reader already knows what to do ;)

[begriffs]

Interesting, maybe it depends on the reader. I tried a channel just now in newsboat and it wasn't smart enough to find the feed, even though I see the page contains

    <link rel="alternate" type="application/rss+xml" title="RSS" href="...">

[rollcat]

I use / have used: NetNewsWire (Mac/iOS), RSSGuard, Miniflux, TheOldReader.com, TinyTinyRSS, and some others I forgot about; I don't think I've seen one that doesn't support this feature. Perhaps you should open a bug / support request?

[dannymi]

It's in the body--but it's supposed to be in the head.