ONE DIRECTION: This letter's "U."

You know it's true.

It starts some words.

There are more than a few-ew-ew.

LOUIS: U starts uh, and ugh and up.

U starts udon.

There's some in this cu-u-up.

HARRY: 26 letters are in the alphabet.

But we're here to sing about U.

ONE DIRECTION: U, you begin the word ukelele.

U, there's a UFO flying by me.

U, and you're gonna feel so unhappy.

I love U, ooh-ooh.

U, you know so you're useful.

U, for unique.

That's a unique gown.

U, check it out, Elmo's upside-down.

U, there's a unicorn dressed as a clown.

Letter U-u-u.

That's what makes you so useful.

Ooh-ooh.

HARRY: That's what makes you so useful.

ZAYN: Don't get upset.

U's what you get.

And when you swim underwater, you're we-e-et.

NIALL: U starts urn.

That's what I've learned.

And a unicycle taught to t-uh-urn.

HARRY: 26 letters are in the alphabet.

But we're here to sing about U.

ONE DIRECTION: U, for utensils in Grover's hands.

U is for uncles, but not for aunts.

U, there are U's on those underpants.

Letter U-u-u-- that's what makes you so useful.

Ah-ah-ah.

[CONTINUES_]

U, you're the ultimate.

Come take a bow.

U, there are artists under that cow.

U, check it out.

It's Bert's unibrow.

Starts with U-u-u.

U, you know you're so useful.

Ooh-ooh.

That's what makes you so useful.

Ooh-ooh.

HARRY: That what makes U so useful.

SINGER IN VIDEO: [SINGING], You sing a song,

and you be a great dancer.

You dunk a ball, and you make the right letter.

Everything you do, you do it better.

This is what you get.

'Cause this is what you get. 'Cause

this is what you get-- with the power of yet.