The most unsettling part is in Facebook's response: “We’ve heard that when accessing their information from our Download Your Information tool, some people are seeing their old videos that do not appear on their profile or Activity Log. We are investigating.” Who wants to bet against their investigation being “how to keep users from seeing it.” Anyone?
I honestly don't understand this cynicism. Facebook does not want your deleted video, and they certainly don't want to keep it given the current media frenzy, with the CEO under fire. Every application of any complexity has features which inactivate, but don't delete data. At Facebook scale, deleting data is non-trivial, and it would be impossible to immediately delete something. We all have bugs, including extremely…
Oh, most certainly they do want that video. Their business is knowing who we are and what drives us, so they can target those ads better. That's what makes their shareholders money.
That the people working there are human beings who might consider it immoral to keep deleted material, is what most people rely on when using such services... but being kind is not Facebook's goal.