Is this "wing-wave" early after takeoff really a pilot tradition?
Is this really a pilot tradition and do they do this on passenger flights and most importantly, was this safe?
  


It wasn't a passenger flight, as the description reads, it was a delivery flight*. Furthermore the plane is a freighter, designed to carry cargo--the kind without feet.

Being a delivery flight, it's typically flown with a very experienced crew, and yes it is a tradition, and it's perfectly safe in that particular scenario (light plane, plenty of performance, no passengers). The crew will also typically let the tower know what they'll be doing, so the tower controllers won't be alarmed.


  The 'wing-wave', a gentle dip of the plane from one side to another, is generally done by cargo planes to say 'goodbye' as the aircraft will never again see the home airport where it was made.


https://www.dailymail.co.uk/travel/travel_news/article-2783901/Captain-dramatically-dips-wings-just-seconds-highly-skilled-stunt.html



* Not to be confused with the maiden flight and the subsequent test flights by both the manufacturer and the customer.

Related question about the same video: Is there any reason spoilers would deploy just after liftoff?