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.
When you looked up accent and dialect definitions you'll find that, Accent is a charactirstic pronunciation.
It's all about sounds. How British people pronounce English words and how American do, etc...
Also, accent is about phonetic habits of a speaker's native langauge. Like you mentioned, how Indian people pronounce English.
But dialect is by definition, A regional or social variety of a language spoken, distinguished by its vocabulary, grammar, and pronunciation, especially a variety of speech differing from the standard speech pattern of the culture in which it exists: eg, the Cockney dialect in Britain.
It is never about sounds alone. When we talk about pronounciations only, then we're talking about accents. If we include the variety of grammara and vocabulary it's about dialects.