With little effort, the woman in the video places the bottle opener against the sealed jar lid, flicks her wrist, and after a little "pop," opens the jar easily.
To accomplish this, place the wine opener against the jar lid with the hook of the wine key under the lip of the cover, then press down firmly with your thumb on top of the opener.
It shouldn't take much pressure before you hear a slight pop that releases the vacuum seal of the jar. You should then easily be able to unscrew the jar lid.