The movie explorer is the best tool for finding nested objects that need editing. The next best approach is to find the objects in the library and modify them from there. Double clicking an object in the library will allow you to edit it on the main stage. Regarding text.........if it is nested inside a moviecllip you simply need to find that movieclip to edit the textfield. If the text is applied by Actionscript, you will need to have the AS panel open and look for a keyframe that contains code or, more often with templates, you will need to select the object with your mouse to see the actionscript code it contains. I dont download or modify others files, but this should just be a matter of digging through the file to find what needs to be edited. Everything in the movie will be in the library.
A mind once stretched by a new idea never regains its original dimensions.
- Oliver Wendell Holmes