Can't get .MOV file I purchased to open

I recently bought 4 videos from various authors. 2 worked fine, but 2 I couldn’t get to open on my computer. All 4 videos were .mov of similar hundreds of MB size. “the item was encoded in a format that is not supported” is all that plays for the two failed files. Has anyone encountered this problem before? As is often the case with a video you pay money for, I do need this file to start working ASAP. Any help is much appreciated. Thanks.

where you open last 2 videos ? in player or in ?
Maybe (one of them) you need update your player ?
If no , contact with this authors and ask them about this )

I think they`ll fast feedback.