YouTube is notoriously unreliable when it comes to records claims, so I am answering this question with a candidate for the longest six in international cricket that at least has a somewhat more reliable reference. I am not claiming this is the record holder.
Mark Waugh from Daniel Vettori, 1997
Test no. 1386 | 1997/98 season
Played at Western Australia Cricket Association Ground, Perth
20,21,22,23 November 1997 (5-day match)
Under the Perth floodlights, which were switched on after tea, the first such use in Tests, he on-drove Vettori more than 130 yards [119 meters] on to the roof of the five-tier Lillee-Marsh Stand, a shot many locals believed to be the biggest six at the WACA ground.
He proceeded to score 86, including a lofted drive from Daniel Vettori onto the roof of the Lillee-Marsh Stand. The ball travelled approximately 130 m, one of the longest sixes in history.
Here is YouTube footage of the shot.