Yes, it will harm your child. Children can only pick up language by listening to people in the room, they can't pick up language by listening to the radio or watching videos. They also can't pick up language from people in the room very well if there is a radio or TV on in the background.
No one is really sure why this is the case, but it is very well proven. (It's called the video deficit, even when you're just talking about audio.)
If this weren't the case then you would be able to teach your kids the phonemes of other languages just by playing audio tapes of native speakers for them, but unfortunately this doesn't work so if you actually want your kids to be bilingual then you need to sign them up for an exchange for age one.
No one is really sure why this is the case, but it is very well proven. (It's called the video deficit, even when you're just talking about audio.)
If this weren't the case then you would be able to teach your kids the phonemes of other languages just by playing audio tapes of native speakers for them, but unfortunately this doesn't work so if you actually want your kids to be bilingual then you need to sign them up for an exchange for age one.