I do not know what Kermitp is drawing of course but I just put a trend line on my chart and the opacity can be adjusted such that it cannot be seen.  that is what I am talking about.  Or the color can be changed to the background color which will accomplish pretty much the same thing.  I am assuming, (shame on me) that he wants to put a lot of stuff on his chart and then show only relevant portions as the video progresses rather than have to add and delete items during the course of doing the video.