Jay-Z and Beyoncé Boogie Down at Lauryn Hill's Concert in The Hamptons: Video

If you didn't already know that Jay-Z and Beyoncé are huge fans of Lauryn Hill, then you certainly will now.

Check out this video, obtained by TMZ ... which shows Jay and Bey eating up every moment of Lauryn's performance Saturday night at The Club House in East Hampton, New York.

We're told Jay and Bey couldn't stop dancing their butts off to Lauryn's live music -- while sipping a few drinks and having a great ol' time.

Our sources say Jay and Bey's daughter, Blue Ivy, tagged along -- and Kelly Rowland and Wyclef Jean also swung by to enjoy the concert.

At one point, Wyclef joined Lauryn onstage, and the two belted out 5 songs, including "Killing Me Softly." We're told the collab was totally "iconic."