I want Flash to play without sound on my machine, and I want that preference to stick so that new sessions don't surprise me with sound. Using FlashBlock while trying to remember to disable sound every time a flash window is started doesn't do the trick for me -- it's too difficult to remember to check the mute status before and after playing videos.

Previously, using Win 7 and Firefox, one could selectively disable sound from Flash plugins using the method described in this question. Older methods of disabling it included the plugin called FlashMute.

FlashMute fails me even when this trick has been employed, and the volume method described in the previous question only works for the currently live session, resetting sound to maximum volume whenever the plugin container is restarted.

What is the best way to disable Flash sound?