I haven't used this library but I took a stab at downloading it and look at the source code. Unfortunately the source code is not documented and it is from 2008!
At any rate, after looking around you can see that the creator gives you two examples that covers both events. One event listens for a custom search and the other one listens for a regular library that you would find in the homepage:
Data API AS3 - First Tutorial
http://blog.martinlegris.com/2008/02/19/youtube-data-api-as3-first-tutorial/
The example above covers a custom search and when you listen for the event you can scan through the results to display them to the user
Youtube Data API in AS3 is ready!
http://blog.martinlegris.com/2008/02/15/youtube-data-api-in-as3-is-ready/
In the example above you can see how the demo does a search for the TOP Videos in Youtube, once you get the results you can display them to the user.
So to recap. getStandardFeed should be used when you look for YouTube Top videos or such, and the getVideos method should be used when you are doing a custom search.