I bought a series of children's educational DVD's and they all have these black lines on all four sides of the picture, throughout the whole video.
This is the first time I've ever seen this. Why would anyone do this? Is there any benefit?
I'm trying to understand the motivation of the DVD's creator for doing this.
FWIW, the DVD's are aimed at a market where a significant part of the consumer base will view them on old/small TV's. Maybe something like TV's that were widely used in the West in the 80's.