So, I didn’t watch this video because I generally don’t like watching random videos. However, I do have a little bit of knowledge on the topic due to recent news that was on (IIRC) BBC News.
It turns out that human jaws have become narrower over time correlated with their eating processed foods, which are much softer than whole foods.
Which is to say that what you eat wouldn’t necessarily strengthen your teeth, but it would strengthen your jaw.
ME/CFS isn’t a subtype of Long Covid. If anything, Long Covid is a subtype of ME. But anyway, they are basically the same condition.