Sorry if that was harsh... get your wife to cut her fingernails and not buckle her joints near her fingertips... the finger should be one graceful curve as if resting naturally. Same goes for the joints between the hand and the fingers. Her hand position here shows lack of control and strength. If you're playing a chord, it's important to be able to weight each key so that the right notes are emphasised, and it's impossible to do this if you buckle your joints. Practice dropping the hand from a great height onto a hard surface, chances are you'll end up with the right hand position, as your hand will automatically adopt a position of strength.
As an aside, the pianist's technique and hand position is just terrible. The shot comes across as a snapshot... the wall next to the piano looks bad and the reflection of the performer in the piano doesn't work well at all. Nothing about this shot suggests a live performance to me. Composition doesn't do a lot for me.