Nicely captured video. Truly a great joy for mom and dad. Adorable child obviously mimicking them well and has the desire to communicate. A fact: Our daughter repeated what she heard at four (4) months old. She is now a graduate of more than one degree and working on another, well adjusted and sociable adult. As for you guys out there "Behind every successful man there's a woman" and each one of those women probably communicate quite well as does the baby in the video.
If you don't understand what the baby is saying its mostly because you're not listening. Her dad understands every word of it, he's obviously a great guy.