Chops can be performed in a number of directions with a number of implements. The cross chop follows a path from low on one side of the body to high on the other side. Either direction can be emphasized for a different training effect, or both can be equally powerful. Possible implements include medicine balls, kettlebells, dumbbells and just about anything with the appropriate weight. The chosen implement should provide a solid way to grip it--a weak grip on the implement will greatly reduce the possible power with which it can be moved and therefore limit the effectiveness of the exercise.
Shown in the demo video is a cross chop using a kettlebell emphasizing the up stroke.