Musescore 1.3 on Mac OS 10.7 crashes at launch

Hello,

I'm using Mac OS 10.7.5. I have downloaded Musescore 1.3 for Mac and tried to launch it. It immediatly complains about this:

So (altough I don't want to watch movies in MuseScore...?) I've activated 32-bit mode for Safari:

But still the same error occurs. And just after 4-5 seconds, no matter if I click on OK or not, MuseScore crashes. I know there are similar issues already reported, but I found none that matches exactly this problem. The crash report is attached.