Since this isn't lossless decompression, the point of having no "real" data is already reached. It _is_ inventing things, and the only relevant question is how plausible are the things being invented; in other words, if the video also existed in higher resolution, how close would it actually look like the inferred version. Seems obvious that this metric increases as a function of the amount of information from the source, but I would guess the exact relationship is a very open question.
The start point. Upscaling is by definition creating information where there wasn't any to begin with.
Nearest neighbor filtering is technically inventing information, it's just the dumbest possible approach. Bilinear filtering is slightly smarter. This approach tries to be smarter still by applying generative AI.
There is plenty of real information: that's what the model is trained on. That information ceases to be real the moment it is used by a model to fill in the gaps of other real information. The result of this model is a facade, not real data.