We have tried to export your project to SWF and uploaded it to Newgrounds and it seems to work fine: www.newgrounds.com/projects/games/1050365/preview
Could you please tell us which steps you did in order to upload the game to Newgrounds?
Maybe you can try to clear your browser cache and try again, And also make sure you are using the main version of the editor and not the beta version.
Please tell us if it worked.
BTW, We have started working on the youtube player. We will keep you posted.
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