Consider upping the cache for youtube. By default it is 2 minutes, which is mostly fine, except that if you are speeding through a part with 2x or faster, you may quickly run out of that small cache, because it only loads with the speed of something between 1x and 2x.
And then you may also set up saving the cache to disk instead of RAM, because it may be quite larger. Single config option.
You can make these only apply for youtube videos only with conditional auto profiles. The doc has an example for an automatic youtube profile, it’s perfect.