I also tested it by putting a YouTube embed with protocol-relative "//" URLs, in a text box, and that worked fine as well.
If anything, it's the *existing* YouTube embeds with the older non-protocol-relative URLs, which are likely to cause problems. But we've opened a separate bug for those: https://bugs.launchpad.net/mahara/+bug/1211583
I also tested it by putting a YouTube embed with protocol-relative "//" URLs, in a text box, and that worked fine as well.
If anything, it's the *existing* YouTube embeds with the older non-protocol- relative URLs, which are likely to cause problems. But we've opened a separate bug for those: https:/ /bugs.launchpad .net/mahara/ +bug/1211583