SIG blocked by firefox

Hi,
Firefox blocks SIG on my website (cannedapplause.de). I can unblock it, but have to do it everytime again I am starting the browser. I guess it’s because my website use https:// and not http. Had the same problem with my embedded vimeo-videos and changed it now and they displayed again.
Can you help me?

Cheers,

Wieland

http://wordpress.org/plugins/soundcloud-is-gold/