I'm going to address two questions here. 1) Can you benefit from Tai Chi online? 2) Is this specific ad a scam?
Regarding question 1) I think you absolutely can benefit from Tai Chi online. I don't think you'll get ripped. But I do think that there's benefit to moving as opposed to being still, and you don't have to perfectly follow the moves in order to benefit from them. This is the approach we take in the cardio kickboxing class that I run: as long as you're moving, I don't really care. I'm not preparing folks for a fight, I'm giving them exercise, and movement is exercise.
Learning Tai Chi online is the same thing as doing jazzercise or whatever else Richard Simmons did back in the day. If you're following along, moving, working, sweating, there are benefits there. It may not get you shredded, but it will be healthier than just sitting in the EZ Chair watching your programs.
To question 2) this is absolutely worded as a scam. "Doctors now seek his advice" is such a cringe comment I wouldn't subscribe just based on that alone. However, here's an interesting video I found a while back on ads and scams such as this.
Corridor Crew is a channel that mainly focuses on special effects and CGI. They have some really fun videos where they sit down with Hollywood stuntment, martial artists, or effects coordinators and watch clips and get inside information on how they were done. They even tested batman's ability to disappear mid-conversation. My favorites of theirs are their "offensive bowling animations" which just get worse and worse in the best ways possible.
In this clip, they're covering an ad and all of the things that are done to keep you interested so you invest enough time in the ad to feel you should subscribe to their service. One of the interesting things I found was how they stretch the progress bar on how long the ad has been playing. It starts off very quick, so it seems like a short ad. But about 1/4 the way through, it slows down tremendously. So what appears at first to be maybe a 30 second ad goes on for at least a half an hour.