Blurry Pillars is what I call it, but I don’t think there’s an actual term for this. Pillars because when footage is ‘pillar boxed’ that’s 4:3 footage in 16:9 with black on the side. But if you layer your footage, same shot underneath, stretch it to fit the sides, and blur them…thus blurry pillars.
Do you think the back ground image is stretched instead of it being the last few pixels of the 4:3 image that is “copied and pasted” to fill in the pillars?