A lot of the gameplay in the early episodes was pretty poorly recorded (using composite and a DVD recorder). If you wanted you could probably re-create it in emulation and get much better quality.
Good point. I mean, the first episode “Castlevania II: Simon’s Quest” is literally just gameplay footage with no footage of the Nerd whatsoever. The gameplay footage may not be suitable for Video Enhance AI, but instead upscaled using a Nearest Neighbour algorithm such as PointResize in Avisynth.