Here are three examples of IB commentaries from youtube.
One thing to do is listen to each one, consider the structure and the main features of the commentary. Why not use the mark scheme given out to you already to mark each one. try and be as accurate as possible.
Click here for a youtube commentary on an extract from the novel The Heart of Darkness
Click here for a youtube commentary on an extract from the play Hamlet by Shakespeare
Click here for a youtube commentary on an extract from the novel The Great Gatsby