You prevent that by stopping any software in userland from being able to access the video path, which is an all or nothing thing. Accessibility is only require

You prevent that by stopping any software in userland from being able to access the video path, which is an all or nothing thing. Accessibility is only required if the app doesn't have system permissions, or if it's not carried out a privilege escalation. Though granted a privilege escalation might also be able to gain root to turn off setting a secure surface too (that's not enough to get past Widevine if that's been used but banks generally are not).