Mom! She is not giving me remote, it has been her limit now, she has been watching TV and you are not saying anything.
She has been watching TV, that's why the TV looks hot.
Does my first sentence imply that she started watching TV in past and she is still watching TV? Can I use "you have not been saying anything to her" rather than "you are not saying anything to her"?
Does my second sentence imply that she started watching TV in past and has stopped watching it?
The first sentence is not quite correct. It should be "Mom! She is not giving me the remote. It has been her limit now; she has been watching TV, and you are not saying anything." It means that she was watching TV in the past, and it implies that she is still watching TV. You can say "You have not been saying anything to her", but that means something a little bit different from "You are not saying anything to her". The first means that during the time that she has been watching TV, Mom has not said anything. The second means that Mom is not saying anything right now.
Your second sentence has a comma splice. It should be "She has been watching TV. That is why the TV looks hot." It means that she was watching TV in the past. It implies that she was watching at least recently. It could or could not mean that she is still watching it.
