If anybody else is having the same issues I've had getting this mod to work, I found an alternate method to getting YouTube videos in your product page:
http://mydigitalfixation.com/how-to-add-youtube-video
It's essentially just pasting YouTube's iframe embed code directly into the product description text editor form (in HTML mode) on the product editing page in Admin.
Works fine, and you also have the added flexibility to select YouTube's extra embedding options such as using https to avoid error messages and the no-cookie viewer for increased customer privacy.
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