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One Direction joined the list of celebrities to appear on "Sesame Street."

Earlier this year, the popular boy band rewrote its hit song "That's What Makes You Beautiful" to be a song about the letter "U" with the new title "What Makes 'U' Useful." In the video, the group explains the sounds "U" makes and different words that start with the letter.

The video with One Direction was posted on Jan. 21 and has more than 2 million views.

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The Clean Cut is a daily feature that highlights family-friendly videos.