The answer is pretty simple, really - but it took some experimenting on my part.
TinyMCE will not do the trick for you. Definitely make sure you clicked "No filtering of HTML" in the JBS Administration/Permissions-Filters button (on the top menu buttons on the right of the Administration view).
Install the JCE editor
Click here for their site
Go to Joomla's Configuration screen and select JCE as the default editor.
Then in your study, click show/hide (upper left), paste in your embed code, then Save the study. You should see a blank window in your studytext where the embed code is. View the site and the code should work. At least it did for me on the localhost version.
Tom