It was a YouTube "live premiere" so once it's over it should be available to watch as normal

Already answered, but for the future, if you tune in in the middle of a live broadcast, you can rewind and watch from the beginning, pretty much like with a usual youtube video. I've done it many times.

The premiere is finished - if you refresh, it should start from the beginning.

I tried to watch last night’s episode on YouTube from the official site, but it seems to start in the middle. How do I get the full episode from the beginning?

Thanks.

Trouble viewing last episode.