Explanation of Bidah According to the Hanbalis by Imam Ibn Rajab Al-Hanbali | Sh. Shadee El-Masry 

Since when is singing and dancing become bidah? We know musical instruments which are forbidden and those who are permitted and even in that there is difference of opinion among the schools of thought.

​@@hxyzazolchaknot dancing itself. But dancing as an act of ibada or part of an ibada like sufis. He gave the example with tawaf. Tawaf= ibada Tawaf with clapping etc= Bida Dhikr= ibada Dhikr with weird headmovements and dancing = Bida

That's not what was said. Maybe it is, or maybe it isn't his opinion, but you missed the point of the video, which is the rejection of the idea that everything that is a bidah is automatically rejected. Certain issues are to be inspected, and scholars have differed regarding them, and the mawlid might be one of those issues. Issues that have legitimate differences of opinion should not lead to takfir or declaring other Muslims with being deviants.