This guy (a protege of Hawking) isn't saying that it is difficult or nearly impossible to know these things. He is saying that the laws of physics as we know them require that we cannot know these things. The information is lost not just to us, humanity. The information is lost to the universe itself. In other words, science states that science cannot know all things about the universe...again, not practically speaking (just give us enough time), but theoretically speaking (even an incredibly old species cannot learn all things).
Science states that the structure of the universe is such that not everything can be learned about it by science.
Now, having said that, we may yet develop theories which allow us to explain the situation better...who knows. But, for now, the best theories we have now say that we cannot know certain things...certain information is just beyond the ken not only of humanity, but of anything within the universe.
[Edit to add this: Don't get me wrong. Science is still the best thing we have to explain the physical universe. I'm not bashing science.]