Accessing the library dynamically

For an upcoming Video Jack project, I’ve been trying out accessing random elements from the library – without knowing previously if they were present there or not.

I found some tutorials/references on the subject.

To find if a class exists:

http://www.kirupa.com/forum/showthread.php?t=334653

To access a class dynamically:

http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/utils/package.html#getDefinitionByName%28%29