Did you ever find a solution to this? I’m having the same issue where the youtube video is very low resolution for the first 3-8 seconds. The issue does not happen with Vimeo, but I really need to use Youtube here.
Thanks @neversettle – I’ve managed to sort it. It was definitely due to the network setup / lack of wildcard subdomains. My host incorrectly told me I should preemptively create a subdomain folder, which is obviously not needed for a multisite set up.
I should add that the cloning does take around 10 minutes and I get the warning “It appears background processing may be getting blocked on the server…”