There are ways on how to do this but for now i will show you on how to use annotations to put your link on Youtube videos.
Here's the easy steps in putting your link in your Youtube video:
1.Login to your youtube account.
2. Go to Video Manager
3. Choose your video then click Edit > Annotations
4. Click Annotation then choose what type of annotaion you want to place on your video. I Choose Speech Bubble
6. Lastly Click Save and Publish
Here's a Sample of Youtube Video with a link placed on it..
On my next blogpost i will teach you on how to put clickable links on youtube.