Make sure that Flash is both activated and up to date.
Safari most likely has disabled Flash as well. You need to double check Safari's setting to see if Flash is permitted, when I update Flash and enable it in Safari's settings the video can be played.
Keep in mind that this is an issue with the format and the browser, not with the extension and a different format (mp4/h264) will not produce this issue.
JoomlaWorks Support Team
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