If the cameras indeed have such low shutter counts you shouldn't need to worry too much about the shutter being adversely affected. The shutter is a mechanical contraption, so moving parts will wear out over time, but there is no direct equivalent physical impact of shooting video. Sure, the camera bodies may have heated up more, but this does not have to result in permanent damages to camera electronics.
It should matter much more how and where those cameras were used, for example in a controlled environment (studio, sports arena, ...) or for example in very cold, wet climate with drastic temperature changes, desert tours or safaris.
