Video appears with Audio but no video

We are developers of desktop software and use QuickTime to display videos through the software (built in Adobe Director). Everything has been fine for the last 16 years but since the recent release of itunes update 11.1.4 http://support.apple.com/kb/TS5376Many of my clients are reporting that the videos within the software are now showing no image only audio.

Details of the video are:

I suspect it it a codec problem.

Updating or changing the video is NOT an option - The product is in the general public domain and is being used by 20,000+ coaches. The amount of video in the resources is upwards of 11Gb so downloading new content through an update is unacceptable.

Is there a fix ?

Can anyone in the know identify the change / issue with an upgrade of itunes ?