What your document demonstrates is the use of the Hyperlink Base. See:
How to create absolute hyperlinks and relative hyperlinks in Word documents - Microsoft Support . Although MS refers to these as relative links, they aren't relative in the true sense. Moreover, using the Hyperlink Base messes around with internal document links also.
PS: As there's no audio in the video - which is low resolution - and nothing in your original post described what you were doing, few would likely pick what was going on.