With the rapid growth of broadband computer networks, users are inclined to use delivery services that can handle large-size content. When offering download service of popular contents, it is more useful to use a multicast system and deliver content to all users who request the content than using unicast system. Using a multicast system, the content server can increase the number of users and decrease user's waiting time. As a result, increasing user's WTP (Willingness To Pay) and the provider's revenue can be expected. In this paper, we suggest two content delivery methods which can be employed in the multicast content download services. We also discuss the provider's revenue of each delivery method. Using user's behaviour model in which a user participates in the service and leaves it, we show the relation between price for the service and user's participation rate of the service through simulation. The relation between price and the provider's revenue is also demonstrated in the simulation. In addition, in each delivery method, we show an optimal price which maximizes the provider's revenue.