Renfield is actually the name of my cat (who, when we acquired him as a feral kitten, was very much like the Renfield shown in the YouTube clip); I just borrowed the name.
Renfield, after many years as a steady and noble cat, is now 19 years old — ancient by cat standards — and he suffers from a feline equivalent of senile dementia. He again does crazy things, only at a much slower pace than before.