It's not skippable as far as I can tell. It also frequently advertises shows I've already watched. Sometimes it advertises the show I'm trying to watch.

I'm pretty sure it also has the "ad counter" showing on the screen during this as well.

Here's what they call it in their docs:

You'll also see a quick preview only once per day before any show to keep you up-to-date on our original programming.

It's not an ad, it's a "preview." /s