In formal English, two negatives = affirmative. But in colloquial English, if some says “I’m never going to do nothing, nohow, noway….” what they are doing is asserting a very strong negative. and in some language, a double negative is routinely a way of making a strong denial.
In serious disputation, it is indeed necessary to be clear, to define your terms and so on. Often, however, a substantial portion of any discussion involves getting to that stage. That’s human nature, I’m afraid, and also the nature of language.
If I may make a suggestion? I would recommend moving on through the logic lectures until the level of understanding really starts to drop, then go back and repeat the viewing. If you do this, you will find that some at least of what was earlier problematic is no longer so. I can’t guarantee that this will happen but that has been my experience over the years.
Keep up the study and thank you for your interesting posts.