Daily fantasy sports gain fans

Fantasy sports are a booming pastime -- and business. Tom Griffiths is a co-founder of FanDuel, the daily fantasy website. Here is how it works: every user has a budget and every player has a price. Build a great team and you could see instant financial gratification.

They have a countdown to week one of the NFL season in their Manhattan offices.

"This is the most exciting week of the year," Griffiths says.  "All of the preparations since January has been building up to this moment."

And fans can win big.  FanDuel is offering one league with a weekly top prize of $1,000,000.

This form of gambling is considered the next generation of fantasy sports: teams you can create weekly, daily or whenever you want. Fantasy experts say this model of gaming is challenging traditional yearlong leagues like the ones you may have with college buddies or co-workers.

FanDuel says that it broke the 1 million active user mark in 2014. This year it is expecting to grow even bigger.

And if you're wondering if this is legal, yes it is.  They are considered games of skill, and not chance, so they pass legal tests.