Do you think there are too many advertisings on TV nowadays?

是的，这句的 advertisings 用得不对。这里可以比较一下 advertisement 和 dvertising：advertisement 是可数名词，指具体的一则广告；advertising是不可数名词，笼统地表示广告，含义相对较抽象。所以网友的句子应改为：

Do you think there is too much advertising on TV nowadays?

或：Do you think there are too many advertisments on TV nowadays?