I recently upgraded from CS3 to CS5 Production Suite and then Snow Leopard. (Macpro 2.66 Ghz). I then tried to export to FLV from FCP6 and the option was missing. I discovered the option was missing from compressor and QT pro also and the FLV component gone from the QT library. I went back through my time machine and it appears to have gone missing with the CS5 install.
Flash will playback an H264 file but if you need to create cue points in the video to trigger other events in flash you need an flv. For FCP users this means exporting from FCP and then encoding again with adobe media encoder. Not efficient.
I found the QT flv component and placed it back in the library. It exports as badly in FCP and QT as it did before. Compressor is the better option. I tried uploading the component here but it didn’t work.
In FCP the progress bar sits on 0% and you get the spinning wheel of death but it is actually working. In the finder you can see the file created and increasing in size over time, you just can’t tell when it’s going to finish until it does. I calculate the file size from the bitrate, wait and watch.
Hope this helps people