Over the past few weeks my email Inbox has been filling up with enquiries from frustrated viewers of my "How To... Embed a YouTube Video into a PowerPoint Presentation" (both versions 2010 and 2013). Initially the problem could be fixed by changing "version=3" to "version=2" in the embed code, but recently this fix did not work. Somehow PowerPoint stopped being able to embed the code provided by YouTube.
It turns out that another fix for the embed code is needed. A viewer on my channel posted this fix today - all it requires is that "http:" should be added at the beginning of each of the two instances of YouTube URLs in the code. the embed code now needs FOUR changes from what is provided in YouTube to work in PowerPoint, highlighted below in yellow: