Developing an Object Oriented Web Service
For this particular screencast author decided to publish the the code in its fullness so that you may play around with it yourself to get a better understanding of it all. See Yahoo Services Demo. One exception you might notice in the demo code (that is different from the screencast) is that author added one extra bit to prove a point of having an onWebServiceSucess.
You’ll see the beauty in the fact that YAHOO.elseWhere didn’t have to know what anyone else was doing with the web service - and all he/she needs to do is set up the Base WebService object and subscribe to the onWebServiceSucess method.