I think the reason why you hear resemblance between this video and old Casio’s is that this particular style of music does involve similar short patterns of a rhythm, simple fills, monophonic lead voice and funny attitude. I had Casio MA-120 and that keyboard was indeed good for this way of playing. But it is just a specific kind of music. It is in fact well played and voices are just fine, including drums.

But I must say that when it comes to demos I am myself very influenced by the music itself, so in case when I don’t like some playing or some tune I may subconsciously decide that I just don’t like the sound - well, music is an influential thing, otherwise what would be a point of it.