This exercise focuses on pronunciation of the vowel written U in French. It is presented in contrast with the vowel I.
Basic phonetic explanations are written below the video.

For students of French as a foreign language

A lot of languages, among them English, do not have the vowel written U in French. Practicing exercises based on minimal pairs of U and I is quite helpful in order to master the pronunciation of the vowel U.

The sound of the French letter I is pronounced like English EE, for example in the word see. I and U are high vowels (the tongue is positioned high in the mouth). Both vowels are front vowels (the bulk of the tongue is situated toward the front of the mouth).

What makes them different is the position of the lips : while I is unrounded (the lips are stretched as in a smile), U is a rounded vowel (the lips are rounded).

You should try to repeat all the pairs of words, and do this exercise twice.