Ask HN: How can Netflix have a bug like this?

Netflix gets into a state for me where, in every browser on my device, the audio plays, while the picture freezes or goes black. I've tried Firefox, Chrome and Safari.

It is fixed on restarting my Macbook Pro, but changing browsers or clearing all cache and cookies does not fix it.

How is this possible? Doesn't it mean that the whole concept of the browser as a sandbox broken? I assume it is somehow a bug caused by Netflix attempts to manage the number of devices I am watching on.

It's such a baffling bug. Does anyone here have any idea of what else I can reset or clear (without restarting the computer) that might fix it?

It happens pretty much every day, and it's quite annoying to have to restart that often.