I am not very familiar with the internals of the video system, so I cannot say why you are not able to at least get at the video. One possibility is that you do not have the appropriate codecs installed on the Spike2 system - you can test for this by trying to view the video file with other software.
But this will not really help you because the Spike2 video recorder puts synchronisation information into the video so that it can be synchronised with the data file. Without that, you might be able to get at the video but it will not be properly synched with the data. Is there any reason why you cannot use the Spike2 video recorder, at least for the future?
Another trick people have used is to have a clock display visible in the video, this can then be used to find the right place in the video but special hardware mechanisms are often needed so the clock is perfectly synchronised with the 1401.
Tim Bergel Cambridge Electronic Design