I recommend "Piano for all"

I don't recommend ANY visual learning app; for ANY instrument. 

Why?
They create a false sense of progress.
They also train you to learn via your eyes; instead of your ears.
Learning visually is COMPLETELY unnatural relationship to music.

You might say
"well so does sheet music"

No:
Sheet music doesn't visually indicate when you play the wrong note.

The purpose of sheet music is just to remind you of what notes to play; not correct you visually when you play incorrectly.

"Well so does video lessons" 

No:
When you are playing along with a lesson... or practicing after... you are hearing whether what you are doing is the same as the instructor.

The added benefit is you can't really practice or learn something that is too far beyond your actual skill level... because you can't keep up or tell aurally whether you're doing it correctly.

IF your ears aren't your principle guide for learning music.
THEN you aren't actually developing as a musician.

THAT is the entire reason we're wise to learn songs by ear.

Lessons is about understanding what you are learning in context; and giving the student structure and direction; to maximize efficiency thus progress.