I empathize with Sidster's point. I think we, Nepali people in general, could improve a lot in our communication skill (Nepali) when it comes to talking about sensitive topics and picking right words so we don’t offend someone unintentionally. In many of Nepali Jamghats, I have heard Nepali Uncles and Aunties and even friends using derogatory terms for Dalits while not noticing there are Dalits in the crowd or may be simply assuming if they look good they can't be Dalit or I don’t know what their logic is.
Regarding this video, I think all they are trying to do is say good things about Narayan Gopal by bringing that accent issue – how he was able to render the sweetest and most popular Nepali songs despite not having ‘regular’ Nepali accent. It is ignorance indeed not bias, not intentionally at least. The ignorance, in their part, was to use the word ‘Tatamata’. Just using this word, they made some people wonder if they are mocking Newari language although I don’t believe they are trying to. Guess what kind of reaction would they get if someone calls Chinese language Chingchong in American media. Its something like that.
Also, I don’t understand why they think Narayan Gopal had accent issue. I guess Narayan Gopal just chose to talk in Newari accent just to give hard time to people lol. Check out this video below (starts at 14.48). He sounds perfect, he has better Nepali than mine (and I get compliments for having suddha Nepali) or many of my friends whose first language is Nepali.

http://youtu.be/rZKrPFnr0uQ