Some bugs are fixed, and more very important features are added to this beta release, specifically the addition of custom mce buttons to the Classic Block is huge and really helpful.

That said, there are so many bugs that I'm convinced that we are going to get a defective product in a few days - here try this:

Create a Columns block and configure it to have 3 columns. Now in each column use the Youtube embed block and embed your videos. Save the page/post, go to the front end, and enjoy the mess !

Things are getting better, but this thing won't be embarrassingly buggy until at least mid 2019 if they continue with this dev. rate. Only then the page builders will be really threatened...