I found that video incredibly unconvincing. It just feels like pseudoscience telling people what they want to hear, and the data was underwhelming (assuming it's not flawed to begin with).
I think a more plausible explanation is that people just lie to themselves to believe whatever they want. These people are only "happier" until they're forced to confront a reality that contradicts their beliefs. In other words it's willful ignorance masquerading as synthesized happiness.
There's also data backing up what I'm saying. There's a study that's regurgitated constantly saying people aren't happier after making a certain amount of money ($75k), but almost nobody bothered to actually read the study. I think this contradictory study is a lot more convincing.