If you've never uninstalled DivX drivers, you may have a lot of them, and don't really know the one is really used. In your situation, I think I would uninstall all of them and only reinstall DivX5.02, or the newly ffdshow. Be aware that when all DivX filters are removed, DivX.dll is able to replace the decoder in it's job! You can also rename the DivX filters one after an other in your system directory and in the BSPlayer\filters directory but its quite a durty job.
Depending of the bitrate of your movie a P3@600MHz may not be enough to play it smoothly.
The Film effect setting you've seen in BSplayer options are intended to setup a new feature of the DivX5.02 decoder. It adds a random noise that looks like scratches. Some movie addicts seems to like that, as some people prefer vinyls analog sound to digital records. A matter of taste.
If you don't have DivX5.02 decoder, I thing it would be worth to download. The decoder, is the same in basic or pro version. If you don't need to adjust color settings, I suggest you to enable "YUV extended mode" and "Overlay extended mode". It will help you to run BSplay in both mode 1&2. And disable "double buffering" and "smooth playback" which are known to be bugged.
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