How to assign Actual Work (completed work) in a task (fixed Duration) in...

How to assign Actual Work (completed work) in a task (fixed Duration).
While assigning the actual work against the task for a week alone in Task Usage, how is the behaviour

You can also watch below link to know How to assign Actual Work (completed work) in a task (fixed unit).
https://www.youtube.com/watch?v=GNeqLNzmKZI