So it looks like in the end it is the irrevocability and the factuality of ‘my’ extinction happening now which keeps ‘me’ in place. There is that common actualist thought (that I am sure many have had, for sure I have) - “oh if only ‘I’ was presented with a button / pill that ensured actual freedom ‘I’ would do it right away!”.
But in this thought experiment / imagination ‘my’ extinction is merely a “maybe” which exists in an imagined future. Now what would actually happen if such a button / pill was presented is that just before the hand presses the button / puts the pill in the mouth there would be that half a second pause - "Is it definitely safe? / have ‘I’ missed something important? / Maybe ‘I’ should ensure X is sorted first? etc. And so the “circling” has begun… And any potential concern would do, it doesn’t matter the particular content of the objection, just as long as it doesn’t actually happen now - “Perhaps ‘I’ will think about it for a little bit and come back to the button / pill later on” And so on it would go and the button / pill would remain unactivated forever and a day.
It’s like that last step into the unknown is a different step than any ‘I’ have ever taken, it doesn’t follow the same rules to any other actions which ‘I’ have ever been involved in. This is what Richard meant that it is the easiest thing in the world and the hardest thing in the world. There is no difficulty to it in a sudorific sense, no great ‘weight’ that has to be shifted, and yet it is so enormous in its implications. And yet as ‘Vineeto’ mentioned in the DVD this “enormity of the implications” is not filled with anything, ‘I’ can’t even know how enormous it is.
But finally starting to accept this is actually great, that ‘I’ cannot know what it will be like, how small or big it is etc. That it is simply an impossibility, so no point even trying, and ‘I’ have tried! 
So I see this is where the thrilling aspect comes in, that it is by definition a movement into the unknown, I think unknowable is actually a better word here - in that it highlights that it is simply an impossibility for ‘me’ to ever know.