I was going to post a new thread about how to make youtube videos embed bigger (to better fit the post), but @dan_fleet clued me into this, so I'll post on here.
My first question is: why is it that the embed on Discourse is even smaller than the smallest youtube video window. Why not at the very least make it as big as their default video size?
I think that the argument about making it taller is a bit of a stretch. This is modern software; and I feel many, if not most people using it have monitors that possess a decent enough resolution where a little bit of extra vertical height won't make much of a difference.
As far as navigating off the page goes, it seems strange to have an embed in the first place if the intention is to have people go to youtube. I think you should be able to have a good viewing experience with these embeds rather than having to go to youtube (or fullscreen). I understand this is how some people use it, but not everyone is the same. I guess my point is people should have a choice of how they want to view the content and right now the youtube embeds are almost thumbnail-like.
Going to add @Ajarn on this as well.