hyperlink

Keep in mind that your published eLearning project needs to reside on an LMS or web server for the YouTube interaction to function. If you publish your project just to your desktop it won't function there.

You can use hyperlinks by highlighting some text and clicking on the insert hyperlink button from the properties panel. It's located under the Style tab as seen below.

Link to the web address of the video that you want to include and make sure you select the option for New.

There is risk with hyperlinks in eLearning. Mostly from distracted learners who are sent to something like a video and perhaps forget they are taking an eLearning course. Also if you use one of the other options besides New (window) you run the risk of disconnecting the user from the LMS.

Same way as for other text: select the hyperlink, take out underlining and change color. There is no special object style for hyperlink text, which is a pity. Reason is that Captivate has only text container styles, not character styles.