Maybe try this?

http://www.w3.org/TR/WCAG20-TECHS/H46.html

I have always thought the code between the embed tags was just ignored (unless it was youtube? ) same as frames or JavaScript.

Indexing robots do not execute code ... While it is possible that some code is measured for "anti spam or web attack reasons" omission for SERP placement is more likely.

And yes, there probably is a thin client "shit list."