In the jokey video address, the dark-haired Sadoun appears to have aged by a couple of decades since taking on the top job, with grey locks and deep wrinkles lining his face.
In contrast, predecessor Maurice Lévy - who stepped down in June - enters the video halfway through, boasting newly-darkened hair and a healthy complexion.
Sadoun, sat perched on a desk, gripping a coffee mug emblazoned with the message, "I’m the boss," states: "As you can see, 2017 has been a long and impactful year. But, more importantly, it has been a year of transformation for us in an industry that is being totally disrupted.
"I know that change is not always easy, and we have changed a lot this year, so I would like to truly and sincerely thank you all for your tremendous efforts. They are making, and will continue to make, a huge difference to our future.
"As we come to the end of this busy year, my message to you is very simple: I wish you and your family a happy, healthy 2018 full of joy and personal success. I hope you will be able to take a good and well-deserved break, and spend quality time with your loved ones. After everything we have achieved together in the last 12 months you certainly deserve it."
At that moment, Lévy arrives on screen, appearing some years younger than Sadoun, and issues a tongue-in-cheek warning to his successor.
"Well, Arthur, I think you should get some rest too," Lévy comments. "And you are right, change is never easy, but it can be rejuvenating too. Personally, I’m starting to feel the positive effect of everything you have accomplished - all in such a short period of time. Merci."
(This article first appeared on CampaignLive.co.uk)