Ran into an obscure bug last night. We had an FLVPlayBack video placed on the homepage with autoPlay set to true. I needed to change the autoPlay to false and since I didn't have access to the FLA I just did it within the code and committed it to SVN for another developer to compile.
Upon playback I saw no errors and thought it worked like a charm. The developer on the other hand was having all sorts of problems with the video playing on top of the homepage animation. It was the same SWF but he was viewing it on a Mac and I was on a PC (both using Firefox). After digging around for awhile we eventually figured out that he needed to set the autoPlay to false in the FLA, instead of in the code. For some reason this fixed the issues during playback on the Mac.
I haven't done any extensive testings, but it seems from these results that you can't change FLVPlayBack component's autoPlay to false in code and then view it on a Mac. You need to make sure you change the component in the FLA instead.