Self introductions like "this is John" are commonly seen on radio and TV (and even youtube) in addition to being a conventional form for telephone.
Radio became widely popular in India before TV and since radio is not a visual medium, announcers might have used 'this is' as with telephone. I suppose this style later carried over to television.
Since youtube is also a type of broadcasting the 'style' may be used on youtube also.
I remember hearing anchors use "this is" to refer to themself on Indian music TV channels like MTV India and channel V as in
Hello this is VJ John signing off on your favorite music show, only on MTV!
This is VJ so-and-so and yaw (you're) watching Indipop Unlimited only on Channel V, etc.
It was supposed to be fashionable 20 years back, but I don't know if they still speak like that today!
'Myself, John' is an informal style that is grammatically incorrect. When introducing oneself to somebody face to face, the widely accepted form of speech is 'hello, I am John.' Some people may also say "my name is John."