We published a blog post on this topic a while ago. https://www.simpleandsoulful.com/blog/how-to-embed-a-video-onto-your-squarespace-website-the-classy-way. and have recently updated it. If you don't want to step away from YouTube completely, you can use a simple workaround to only display related videos from your channel. This is better than nothing, but still gives visitors the opportunity to click away from your website and on to YouTube. We find this works for our clients in some instances, but when we are building a homepage, landing page or a sales page where you definitely don't want to lose or distract visitors, we recommend using a Vimeo Plus account.