The reason I noticed it is that the two cities, though very close geographically, have an intense and not entirely friendly rivalry that goes back hundreds of years and continues to this day. See for example the History section of [0]. Although it's understandable that someone not familiar with the area could confuse the two places, friends from Sunderland tell that they are pretty offended when they are mistaken for Geordies. I imagine it's like accusing Bart Simpson and his friends of being from Shelbyville.

[0] https://en.m.wikipedia.org/wiki/Tyne%E2%80%93Wear_derby

EDIT: Please forgive me for bringing this up. I appreciate it's not particularly relevant to moomin's comment about the culture of the Nissan plant, which I agree with aside from my nitpicks, nor to the original video.