"...Please note that for security reasons, some host providers
pages; this is a known issue for WordPress and a number of other
blog hosts. In this case, you can insert a captioned YouTube video
followed by an explanation on how to do that.
Google Sites seems to be yet another platform that doesn't
support the Amara / Universal SUbtitlesembed code.
However, I'm just a user like you and yesterday I noticed that
the Help tab in Amara / Universal Subtitles now links to a new
section, and not to this tenderapp one anymore. So you might wish
to ask your question there too.