How to Make Money Off YouTube Videos

I interviewed people in the street in London and edited the footage into a series of five videos which I published on YouTube. Part one now has 1.6 million views and part two has a million views, not bad. The reason for that is well that's another story for another time really but to make money off YouTube videos, first of all you need to monetize the video. Some of those videos in that series I couldn't monetize because of certain bits of background music. So anyway for various reasons I didn't make loads of money from those videos.