The first step for using Lightning Out is creating a dependency application. A dependent Lightning Application extends from ltng:outApp. Note that extending from ltng:outApp also involves incorporating Salesforce Lightning design systems. If you want your Lightning Components not to have design systems imported in Lightning Out, then you can use ltng:outAppUnstyled.
The following is a code snippet for the dependency application that exposes the youtubesearch component:
<aura:application access="GLOBAL" extends="ltng:outApp"> <aura:dependency resource="youtubesearch"/></aura:application>
The <aura:dependency> tag enables you to declare dependencies. If you are using any event, such as force:navigateToURL ...
