When I click on the VOD, a message 'An internal error has occurred in the completion system. (The system administrator can enable debug information for more details.)' appears and it is unable to watch the VOD.

https://support.coursemos.kr/attachment/view/431/clipboard.png

It is an error caused because 'Grade Require' is included  in the Activity completion condition, while the VOD has not being added as a grade item.

There are two solutions. Check your VOD settings.

1) Activity Completion -  Grade Require Unchecked

When you are not adding the VOD as a grade system, set 'Grade Require - Unchecked' in Activity completion.

2) Add as Grade Item - Yes

When you are adding the VOD as a grade item and set it to be completed when grades are given,

set 'Add as grade item - Yes' in Grades and 'Grade Require - Check' in Activity completion.

(Note) In general, VODs are checked for 'Learning time Restriction' under the Activity completion condition.