Hard to know, but if I had to hazard a guess, I'd assume that it was Apple's ProRes codec. You didn't say if you were on Windows or Mac for CS4, so again, I'll assume Windows:
Apple ProRes QuickTime Decoder for Windows.
Now, if it's AIC (Apple Intermediate Codec), you're out of luck--there is not decoder on Windows for AIC. If it's another codec altogether, you're going to have to do some sleuthing. I recommend
MediaInfo, a pretty indispensable tool for video file exploration.