Convertible Debenture

The answer in the lecture notes is different to the method of calculation in the video. Could you please explain the correct answer as when working through the amortisation using the answer in the notes the resulting closing balance in year 3 results in $0.018m whereas if you calculate all three years using the video figures you get a closing balance of $4.19m. So it seems that the explanation in the lecture notes seem the most appropriate. Or are both methods of calculating acceptable.

Thanks.