Analysts estimate that last year consumers spent more than $50 billion on virtual items in video games like Counter-Strike and World of Warcraft. This lengthy but highly informative video explains why the market for virtual items has grown bigger than global box office returns for the movie industry. 

Questions:

1. How are in-game economies similar to real-world economic systems?
2. What are the advantages and disadvantages of online marketplaces that sell virtual goods?