If you meant the window in the screenshot, then my suggestion and yours lead to the same window. I just meant that I don't know which option to choose. I guess I should select Take no action in the drop-down menu for Mixed content.
You want to turn off auto play,you only have two choices, take no action, or ask me every time, try take no action, do what you where doing, and if thats not the one, try ask me every time.
If you're using an external card reader you should be able to plug it in (probably should make sure it has a card in it to be sure) and then find it under "Devices" at the bottom and choose "no action" for it specifically. If it's built in to your computer, or for some reason doesn't show up under Devices as an external reader, then setting the mixed content option to no action instead may work. If it doesn't, you can always switch it back Alternatively, you can just disable AutoPlay altogether, if you don't use it for other devices.