如何安全地嵌入任何flash文件（swf）？

I want to allow my users to embed their own Flash animations in their posts. Usually the actual file is hosted on some free image hosting site. I wouldn't actually load the flash unless the user clicked a button to play (so that nothing auto-plays on page load). I know people can make some really annoying crap in flash, but I can't find any information about potential I want to allow my users to embed their own Fla