Are you sure that you want to play a DirectX clip or are you saying that you want to use ActiveX to play a movie inside of CVI?
I highly suggest doing the latter, because it is far easier. With CVI 6.0 you can even embed a Windows Media Player ActiveX control inside of your user interface to play the movie, and the WMP object interface does have several methods for retrieving current position and the like that you could use to figure out when to pulse your parallel port.
To find out more about using ActiveX controls inside of your UIRs in CVI 6.0 you can look at the example inside of your ...\measurement studio\cvi\samples\userint\activex.
Jason F.
Applications Engineer
National Instruments
www.ni.com/ask