The pure written form of Bengali Cholito Vasa is taken from the Kustia/Nodia region as the standard in 19th century.
When you will speak to a Kustia/Nodia region person, you will know how stupid you speak in Kolkata.
Note, how a person originally from a far away Noakhali, but living in WB, is trying to showcase himself as an expert of Bangla dialect. Now, I find he does not even know where Kushtia is located. Sharat Chandra Chatterjee has certainly adopted the Kushtia dialect for his novels, but these guys even do not know that. They think we are emulating WB dialect. Kushtia way of speaking is very beautiful, in which we try to speak and not WB's Ghoti accent. Ghoti accent is horrible.