First, the reading says that farmers cooperated to maintain the lands by sharing the cost and labor equally. On the other hand, the speaker states in the lecture that people did less labor because everyone thought that someone else might have maintained lands. As a result, farmers became neglect and the productivity decreased. This contradicts what the passage indicates.
Second, the passage mentions that commons prevented overgrazing because people were careful not to take more than their share of
the grass. However, the lecturer claims that there were incentives for farmers to overuse the lands. They came to get thier cows to eat as much grass as possible before neighboer did so, which the author of the reading might not have predicted.
Third, the reading states that it was easy for new comers to take part in the agricultural actibity of the villege thanks to commons. By contrast, the lecture says that, becuase of overusing, there was no grass left for new settlers. This is another part that contradicts what the reading says.
Therefore, the main points made by the professor in the lecture cast doubt on the points made in the reading passage.