1) The student actually might have learned(played) the VOD only for the recorded time.

2) Check the student's learning environment.

This can happen when the student attempted to learn(play) by opening the window, but closed the window after a certain amount of time elapsed without actual playback.

The state in which playback does not occur(the state in which progress is not checked) is as follows.

• When the network connection is not smooth
• When the device such as PC or laptop is in standby mode

EX.