Google adsense is a popular ad network.You can place your ads at your website by signing up with google adsense.Similarly you can also earn from your youtube videos.If your video has good views,then you can earn by displaying your adsense ads at Youtube videos.You can do this with following procedures.
Earn Money With Youtube Videos
First Sign in at YouTube
Then click in the my account tab
Then you need to click onAdSense Account Settings under quick Links to Partner and Ad Programs
Then through your adsense account manage the settings.
Or you can follow the shortcuts
Sign in to youtube and
click this link
and now set up adsense settings
Best of luck.