The answer to your question is
In order for this designer to create a program that will convert VHS to 3D, he needs to understand all of the aspects of VHS film. How he will get it to be converted and how to keep good quality. He must understand where the film is stored in the VHS tape and how it operates to transfer it's content to the playing device. He can use all of this knowledge to develop this program to perfection.
I hope this helps!