It cited research finding correlations between marriage, multiple personal relationships, happiness, longevity, and physical activity. They said that relationship and exercise cause happiness and long life. Money helps also.
My guess is that it is the other way around. Healthy happy people attract friends and spouses. The longer-lived people exercise more because they are healthy enough to do it.
No one wants to be around unhappy people. The unhappiness comes first, and then the relationships go bad.
The guests on the show seemed very scientific, except when they contradicted each other. And they really didn't have a scientific argument for causality
Supposed you picked 1000 people at random, and then randomly arranged for half to get married and the other half to get divorced or stay single. And then you did followup studies over 20 years to see which group was happier. This might give evidence for whether marriage causes happiness.
Nobody has done such a study, of course. But we can do studies of lottery winners. The winners are randomly made rich, and can be compared to a control group of losers. This might tell us if a monetary winfall leads to happiness. The video implied that it does not, but it was not clear. At one point it said that happy people can become even happier, with more money.
The video claimed that married men live 12 years longer than unmarried men, so marriage adds 12 years to a man's life. It is hard to believe that marriage could make so much difference. I think that women like to marry healthier men.