It also doesn’t seem to understand HTTP 2 push. Any pushed CSS is ignored and counted as a separate HTTP request.
These tools are indicative and not gospel. My own site ( https://r.je ) scored lower than it should have on pagespeed for years because of “render blocking CSS”, even though it used HTTP 2 push to send the CSS as part of the first request. They’ve fixed that now though and I get a nice 100 score
YouTube video embeds are pretty well optimized. So, they do not actually lower the page speed. You can use SEO embeds so it communicates to bots that your site is hosting a video.