The answer to this question can be explained by understanding the concept of supply and demand and their relationship to the equilibrium price.

Supply and Demand:
- Supply refers to the quantity of a product or service that producers are willing to offer for sale at different prices.
- Demand refers to the quantity of a product or service that consumers are willing to buy at different prices.

Equilibrium Price:
- The equilibrium price is the price at which the quantity supplied equals the quantity demanded.
- It represents a balance between the two forces of supply and demand.

Below Equilibrium Price:
- If the price of a video rental is set below the equilibrium price, it means that the price is lower than what the market would naturally determine.
- At this lower price, consumers would be willing to buy more video rentals, as it becomes relatively cheaper.
- On the other hand, suppliers would be less willing to supply video rentals at this lower price, as their profit margins would be reduced.
- Therefore, the quantity supplied would be less than the quantity demanded, leading to a shortage in the market.

Above Equilibrium Price:
- If the price of video rentals is set above the equilibrium price, it means that the price is higher than what the market would naturally determine.
- At this higher price, consumers would be less willing to buy video rentals, as they become relatively more expensive.
- However, suppliers would be more willing to supply video rentals at this higher price, as their profit margins would increase.
- Therefore, the quantity supplied would be greater than the quantity demanded, leading to a surplus in the market.

Explanation of the Correct Answer:
- The correct answer is option 'A' because it correctly states that if the price of a video rental is below the equilibrium price, the quantity supplied is less than the quantity demanded.
- This is because a lower price would incentivize consumers to buy more, while suppliers would be less willing to supply at that price.
- Similarly, if the price of video rentals is above the equilibrium price, the quantity supplied would be greater than the quantity demanded, leading to a surplus.

Conclusion:
- Understanding the concept of equilibrium price and its relationship to supply and demand is crucial in analyzing market dynamics.
- When the price is below the equilibrium, there is excess demand or a shortage, and when the price is above the equilibrium, there is excess supply or a surplus.
- Option 'A' correctly captures this relationship by stating that the quantity supplied is less than the quantity demanded when the price is below the equilibrium price.