avipreview is a utility that extracts audio / video frames. if he is missing 2 files, then the problem seems to be extracting the first 48 without thte 2, and then viewing them. i have no idea about how the extract works - but there is probaby some kind of option to "not delete corrupt files" to make it extract what it can from an archive. i'd try and extract with all but the last 2 in the directory, and see what it says.
if you can get a file to work with, avipreview constructs a video feed out of whatever parts are present.