The Select buttons not working is REALLY strange. All they do is attempt to open the standard Windows file dialogs (file open & browse for folder). There's very little code in there and it's not complicated stuff. Even if they don't work you should be able to put the path to the file you want into the text field (by just typng it or using copy and paste).

Is there anything "different" about your XP install? Is it running in a virtualized environment? Do you have any shell extensions installed that interfere with the Windows file dialogs? What (if any) anti-virus software are you using?

SWF Studio will let you play video files (other than FLV) as long as the codec you need is installed on the machine. In that case you wouldn't need to convert your files to FLV format and you can get notifications when a video finishes for advancing to the next frame in your timeline.