There is no "songs.txt" file how can the program run without throwing something like FileNotfoundException???

OK.. but first it imports when there is no song.txt file it should first export then importffrom. like..

public class Karaoke {

public static void main(String[] args) {

SongBook songBook = new SongBook();
songBook.exportTo("songs.txt");  // this will create a file songs.txt
System.out.println("Saving book...."); 
songBook.importFrom("songs.txt"); // here we can read it when the file songs.txt has been created 
KaraokeMachine machine = new KaraokeMachine(songBook);
machine.run();  

} }

Yes, and the first time the application is launched an error does actually occur as you can see at 9:18 in the video. But there is a catch clause setup for the exception which is why the program does not crash. I assumed you were asking about why the error did not occur the second time the application was launched.

It was printed above the stack trace, the stack trace is just so long that it pushed the printed string above what you ended up seeing of the console in the video. If Craig had scrolled up when the error occurred you would have seen the error message string at the top.