I share everybody else's high opinion of "The World at War." I haven't watched it all the way through (I'd certainly like to), but all the episodes I've seen have been of extremely high quality. About the only weakness of it is the simple fact that it's so old. (According to the Barnes and Noble website, it was produced in 1973. That means that, for example, it doesn't say anything about the "Ultra secret," and none of the interesting research done over the past 37 years is reflected in it.) That's not a criticism; just something that needs to be taken into consideration when watching it.
The university history department where I work has a copy of the whole thing on VHS tape. It's getting pretty old now, but it gets a fair amount of use. I'm not competent to talk about whether it would be acceptable in public school classrooms all around the country, but it would here in North Carolina. (My wife is a high school history teacher.) The policy around here is that teachers can screen any movies they want, but if the film is rated "R" (or, I suppose, "X") they have to get a "permission slip" from each kid's parent allowing the kid to watch it. (The initiative for that policy came from the parents - not the teachers or administrators. My wife rarely has any trouble collecting the permission slips - though some of them are probably forged. The only big problem she's ever had was with a family of Mormons, who utterly refused to let their kids - who were good students - watch R-rated movies.) "The World at War" is designated "NR," so it wouldn't be subject to the rule. "Saving Private Ryan" is used pretty frequently in high school classrooms around here.
I confess I personally have somewhat mixed emotions about that particular issue. I remember when "Glory" came out on video. My stepson, who was 12 at the time, watched it with his mother and me, and showed little interest in it. The next day we walked into the living room and found him and a couple of his friends watching, over and over, the scene near the beginning where the Union soldier's head gets blown off. Later I took him to see "Gettysburg," which contains quite a bit of pretty good history but scarcely any gore. Admittedly the kid was a little older by then, but during the intermission and after the movie was over he pummeled me with questions like "What would somebody like me have been doing during that battle? If I'd been old enough to join the army, which side would I have been on? When that general said 'there are times when a corps commander's life does not matter,' what was he talking about? Why did those guys march across that big field in straight lines?" Etc., etc. I felt like the ticket money had been well spent.
Personally, as a college teacher and an historian by profession, I want young people to be aware of what a horrible and gruesome experience war is. (If they have nightmares about it, that seems to me to be a healthy reaction.) But I also think there's room for movies that, without sanitizing the story beyond recognition, put the emphasis on other aspects of it.
The bottom line, though, as far as I'm concerned, is that anything that gets kids interested in history is a step in the right direction. (As I tell my museum studies class every year, the typical American teenager is interested in precisely six topics: automobiles, rock music, beer, marijuana, sex, and sex. Getting him or her to take the slightest interest in anything else is an almost impossible challenge.) Next week I'll be confronting yet another classroom full of college freshmen in a U.S. history survey course. On the first day of class I'll pass out a preliminary survey, in which I'll ask them such questions as "In what year did the American Civil War end?" (About five percent will know the answer.) And "Name two countries the United States was fighting in World War II." (About twenty percent won't be able to name one, and ten percent won't be able to name two.) And "Which side, the North or the South, did the United States support in the Vietnam conflict?" (At least twenty percent will get it wrong.) I have to remind myself that most of the people in that classroom were born during or after Operation Desert Storm.
I feel old.
Later edit: I took another look at the B&N website. "The World at War" normally sells (to B&N "members") for $89.95. But when I clicked on "Used copies available from our network of booksellers," I found a copy - brand new, still in the factory shrinkwrap - for $35.00! Needless to say, I ordered it. What a find!