I always see this Giovanni Stanchi piece used to show the “evolution” of watermelon. So, in the video, the guy is talking about how this particular watermelon, the one in the thumbnail, looks different “from other varieties.” The reason for this, which isn’t covered in the video, is that the Stanchi piece shows a watermelon with “hollow heart,” from its poor growing conditions. Usually because of a late season cold spell that inhibits decent pollination or possibly a lack of adequate sunlight. When you look at climate data, you also see that this painting was made was during the Maunder minimum, which may have been a contributing factor.