It turns itself back on for me so frequently that I'm sure they must be intentionally having the site reset that preference... I hate it with a passion.

Now when I go on mobile Safari and want to switch off 'video previews' (for the thousandth time), and I tap the switch, it stays switched on but the 'Settings saved' thing comes up on the bottom. You have to tap it again to actually switch it off. I wonder if that's a bug or intentional too now...