This is such a juvenile video comment.

Language, and the ability to express oneself, relies on precision. If you are unable to be precise (say, because you are new to a language), then you lose essential aspects of communication, including your own agency.

'Less people' is imprecise and there are examples where that ambiguity dilutes the intention of the speaker (bad example, but I can't think of any good ones off the top of my head: telling a doctor that you've got 'less headaches' could imply that the severity of headaches has reduced, not the number even if you meant the number of headaches...and that can lead to a wrong diagnosis).

On the word 'literately': I hate the use of it, but it isn't grammar. It's the meaning of the word, and meaning changes. Grammar, however, only changes when it rules serve no purpose, which - in the case of 'less' and 'fewer' - isn't the case: the rule serves a vital purpose.

And finally: I hate it when literate people with good jobs spread this kind of laissez-faire attitude to language. Yes, fine, you're doing just fine, but 'street kids' need agency to achieve and you are giving them an excuse to relinquish agency. You encourage them not to give a damn about language (it's all good bruv!). It's deeply irresponsible.