Why do people assume there would be "legal complications?" Why the assumption that they just took what they wanted without licensing? They're not obligated to inform us about these arrangements, the licensor has no interest in disclosing what its licensee is up to, and the licensee can say (or not say) whatever it wants.

Do you actually need any kind of licensing or permission to sample 10 seconds of a song? Especially when the end result sounds nothing like the original

Yes, you do. Legally speaking. Which means if the song makes money and is popular, and your samples aren't covered, you can get fucked hardcore. Regardless of how long the sample is.

TFA says "More Spell On You" was cleared.

No need to be rude. The video itself implies that the sample wasn't cleared. I wouldn't expect everyone who saw this post to watch the video AND read the whole thing. Still, you're right of course.

Rude?

Yes, surprisingly, using an acronym like "The Fucking Article" might be construed as rude in certain circles.

TFA often means "the full article", even though the more rude sense is more common elsewhere.

I’m sorry, but you cannot use “TFA” without implying “The fucking article” at least to some degree. That’s just how it is, never mind the intent. If you want to be polite you do not use “TFA”, it’s as simple as that.

or you could give the poster the benefit of the doubt and read it as "the featured article". It's your decision how you decide to read it.

The Featured Article

That makes sense, as to why they didn't need to publicly disclose use of the sample. Still licensed, just not publicly disclosed.

There are a few other tracks off Discovery that are like that.