Canon ixus 75 problem?

Can someone tell me why I cant download one video off my camera,it lets me download the pictures and other videos but cant seem to find this certain one.I could understand if it was a cheap sd card but its a sandisc extreme III.Somebody told me it the format,not to sure what this is.I've also tried loading it through a card reader but no luck.Any ideas how I can download this or avoid this in the future would be gratefully received

Bryan