That was a really interesting video so thank you for sharing. I learnt a lot (and recommend it for people with kids with ADHD in particular).
He doesn't say so, but I can believe that Dr Berkley may think (and may have definitively said more recently) that emotional dysregulation should be a required criteria for an ADHD diagnosis [Using my layman's example this would get him saying that it you don't have pain in your foot, it's not a blister even if there's a lump]. He certainly believes it's fundamental to the condition and that the lack of recognition of it leads to misdiagnosis if other conditions (particularly ADHD emotional dysregulation being mistaken for mood disorders) and that it is key to treatment options for both ADHD and some comorbid conditions (particularly ways to prevent ODD developing into a social disorder).
But what he doesn't say is any of these two points you've made:
However, it is well document that these criteria are not complete, for example, (emotion) dysregulation which is at the core of ADHD was
purposefully taken out of the criteria in one of the last revisions as an attempt to make diagnosis easier for certain professionals
And
The requirements to meet for the threshold have been waterdown to make diagnosis (ensuing support accessible to those who needed it) that’s why it’s brought up. The criteria are to not thrrr to facilitate the assessments as it is a fact that that not all assessors are equal in the expertise, knowledge or training. But those criteria do not reflect entirely what it is to live with either or and it is misleading for people to try and understand it
Even putting aside the fact that, whilst he's not a young man, I doubt he thinks that a 1968 revision is a recent revision, he literally says nothing about watering down if diagnostic criteria to make things easier for clinicians. In fact he doesn't reference the way ADHD is diagnosed at all.
I don't think it's worth doing much further on this one. Whilst it's possible(albeit pretty unlikely) that the reason that when the DSM was introduced in 1968 it didn't mention emotional dysregulation to make it easier for clinicians to diagnose, it's not really relevant to any discussion now, and given the extensive revisions to the DSM since then I find it really hard to believe that would be the main reason it's not in there now and people wouldn't be shouting about it (plus more it's not really in psychiatrists interests to make diagnosis easier for clinicians with limited training - puts them out of a job!). And it's certainly not relevant to this thread which is about how clinicians can tell ADHD and autism apart.