I watched the portions of the videos that you provided. To preface my response, I’ve learned a lot from Jethavanarama’s videos over the years. In fact, they were instrumental in getting things to click into place for me. Having said that, these definitions that Amadassana Thero provides for the three characteristics of nature don’t grok for me.
One issue (among others) with translating anicca as impermanence is that it becomes necessary to ask a follow-up question; “What is the significance of things being impermanent?” or put more bluntly, “Okay, so what?”.
In a similar way, I can’t help but feel that the significance of the proposed definitions is buried.
To illustrate my point, suppose that you are drinking a liquid due to being thirsty. I then inform you that there is an issue with the liquid – it doesn’t have the capacity to quench your thirst. You would then think to yourself, “Huh. Well if that’s true, drinking this liquid is a complete waste of time”. This is to say that the relevance of that statement would be self-explanatory. Now, you might not believe my claim, but that would be a separate issue.
I’m willing to concede that I’m missing something and that I simply need to ruminate on it more. But this is how I see the matter currently.