YouTube has added a feature under video manager called "cards". Cards are links you build on your video once uploaded to YouTube.
I think the most important "card" is adding your Website link on your video. In order to link a video these steps are required.
Sign into YouTube and go to Channel Settings/Advanced. Under Associate Website add your Website URL including http://www.example.com Then Google will ask you for Verification.
Once you complete step above. Go to video manager click edit on one of your videos. Click "cards " at top. Screen shot below.
When you click on Cards this page opens.
Click on cards. Choose Associated Website. This completes the steps to link your Website on the video. Good Luck. Comment if you need help.