Unit Testing for C# Devs - Creating Moq Objects

Hello guys, in Unit Testing course on the lesson about Creating Mock Objects using Moq, Mosh give us an example of testing ReadVideoTitle_EmptyFile_ReturnError

My questions is: How can I test the other scenario, where the video title is returned?
I tried to Mock the same way but Im get an error with msg “Newtonsoft.Json.JsonReaderException : Unexpected character encountered while parsing value: M. Path ‘’, line 0, position 0.” Like the compile is looking into real file

Has anyone tested this scenario using Moq?