Rated 5 out of 5 stars
Great addon. Wouldn't upgrade from v23 or wouldn't use FF if I had not found this.
hoboX10, find this setting in about:config "plugin.sessionPermissionNow.intervalInMinutes" and set it to 0. Now FF will remember your choice for 0 minutes, effectively doing exactly what you (and I) wanted. Still this addon is necessary for the per-element part.
I modded it a little to display dashed border around the clickable elements, just as it was in FF23 and before.