Notes

First, I watched the YT link you sent. All I can say, being a native doesn't mean you know everything about your language without studying it. You can't simply explain Arabic grammaer just because you speak it. So I don't know if this girl is an English teacher or else, her explanation could be wrong.
Accent definition is: A characteristic pronunciation, especially:
a. One determined by the regional or social background of the speaker. eg, British accent, American accent.
b. One determined by the phonetic habits of the speaker's native language carried over to his or her use of another language. /It is about one's personal accent in a second language. It's about "individuals" rather than group of people. like you said, Indian English.
Dialect definition is: A regional or social variety of a language distinguished by pronunciation, grammar, or vocabulary, especially a variety of speech differing from the standard literary language or speech pattern of the culture in which it exists: Cockney is a dialect of English.
Or a form of a language spoken in a particular geographical area or by members of a particular social class or occupational group, distinguished by its vocabulary, grammar, and pronunciation