Hi, If you have a adsense account and a youtube account and you have more than 200 subscribers, get lots of views in your videos then you can start putting ads onyour videos and everytime some click on that ad you get money. I think this is a good way to earn money but you need to have alot of requirements. And the response takes for ever i sent them a Email to become a youtube parnert (that is what is call) and they told me no 2 weeks later!!! Want to become a youtube parnert here is the link... http://www.youtube.com/partners And you get more feature.
I applied - and got denied because my channel is 'prmoting a business' - seems most channels ARE in fact - promoting a business . . . . hmmm.