Nitai or Nityananda was a Baul and he was from Babukishan's family they have the stories that are not known regarding his lineage, they have never been revealed because of what has happened to Vaishnavism in Bengal, Vaishnava Bauls never rich temples or collected devotee's, they are an oral lineage so there was no need to sell book.
Nimai is Sri Chaitanya, this is the story of his life. The songs or kirtan in this film are Lineage Vaishnava Baul kirtan. The second little boy and mother carrying the ektara or Gopi Chand which little baby Chaitanya is crying for is Sri Nityananda who was a Baul and later in the movie when they are older Chaitanya meets Nitai again you can hear the ankle bells that the Bauls have always worn for thousands of years and you can see Nitai was a Baul who wandered and sang Baul kirtan.
Chaitanya was not a born Vaishnava but he had great respect for his Guru's in which he had 108, Sri Nityananda was one of his Guru's and he had great respect for him as a Vaishnava Baul. There is so much that has not been revealed from the oral tradition of Vaishnava Baul and most of what is taught today by modern Vaishnava reformers is a mere drop in the ocean of this ancient tradition called Lineage Vaishnava Baul Gosai Das Baul and Gosai Dasi Baul.