You can see he demonstrates these "random" tourette symptoms. The linked research states how experts looking at these videos have identified them as way beyond the normal tics of someone with Tourette's, and they change and have context across videos. They're not exactly calling the YouTuber a fake, but it's somewhat implied. The videos are cut and edited in a way that highlight the "tics" and the popular ones are even sold on merchandise like T-shirts.
If I'm reading the paper correctly, they've attempted to treat teens demonstrating these symptoms as if they were treating Tourette's and it didn't work. It's some type of illness related to identity and attention-seeking enforced by social media. So they're saying teens see these types of videos and start imitating the behavior as part of a mental illness.