if my boss said, "hey i've been watching you on my nannycam and you need to do more with my baby, instead of just the basics of caring for her" i might get a little defensive. just be super nice about it.
honestly i feel like nannycams are more for ensuring the physical safety of the child...this seems borderline nitpicky to me.
maybe avoid the whole topic of judging her performance, and just make flat out requests. "i was hoping you could take the baby on a walk today, he hasn't been outside lately." "sometime today would you mind getting on the floor and playing with him with these blocks? he really loved them last night when we played with him."
*after reading other responses* i agree with Marda that at 10 months old there's not a lot of structured play required....he's a baby...let him be a baby. as long as he's happy and thriving. i don't see where 10 months is the time to really worry about enriching activities, etc. everyone is different (case in point the 10 month olds fluent in sign language) but to me it's really not necessary.