Not bad, though I think this one was a bit too similar to Firth's work.
Imo, the 'sibling' looked a bit like Homestar Runner. Was that intentional?
Also, I do appreciate the nod to the true classic piano piece of our time, but I felt it was not quite earned like it was in Salad Fingers 4. Perhaps of you had made this longer and given its 'story' time to expand.
Keep making things. You are on the right path.