Generally when people say elsewhere they are referring to Youtube hosted videos. Youtube has a multi-billion dollar edge network. Which means that there is a good chance you are playing youtube videos from a mirror only a couple miles away from you and probably on your ISPs network, leaving very little potential for any problems.
Other edge networks, such as Amazon’s, only provide a few mirrors per continent. In Australia we only have two, which means that there are many ISP dependent issues that can occur.
We do our best to use technology partners that can help eliminate these issues but without budgets like Google can afford we can’t completely eliminate issues like this.
The upside is that if it happened out of nowhere it generally disappears out of nowhere when your ISP finds their issue or after enough complaints.