Shouldn't the following sentence "Due to the graphic nature of this footage, viewer discretion is advised." technically be "Because of the graphic nature of this footage, viewer discretion is advised." You only use "due to" because it means "attributable to." We wouldn't say, "Attributable to (= Due to) the graphic nature of this footage, viewer discretion is advised." (Technically incorrect, grammatically speaking, yes or no?) Compare: His illness was due to (= attributable to) a virus. Because of his illness, he was out of work for two weeks. Not: Due to (= Attributable to) his illness, he was out of work for two weeks. Thank you.
I think the difference in meaning between the two is just too fine and too arguable. They sound equally fine and interchangeable to me. There may be speaking regions that give them a more distinct meaning, but not in mine.
You would use "because." That's because "due to" modifies nouns, whereas "because of" modifies verbs. There's actually an easy way to determine which phrase to use. Let's use what you have as an example. "Because of the graphic nature of this footage, viewer discretion is advised." The first step is to remove the phrase that begins with "because of" or "due to." So we're now left with "viewer discretion is advised." If it makes sense to turn that phrase into a question using "Why," then you would use "because of." In this case, the phrase can be turned into a question that makes sense: "Why is viewer discretion advised?" So we know to use "because of." Let's now use your other example. "His illness was due to a virus." Removing "due to a virus," we're left with "His illness was" Rewriting this as a question starting with "Why" doesn't make sense: "Why was his illness?" So you know not to use "because of" in this case. That's just a quick and easy way to determine which phrase to use if you have trouble thinking about what I wrote in the first paragraph.
i'm with wrey on this... either one is acceptable... they mean just about the same thing... there's not enough difference in meaning to justify banning the use of one in favor of the other...
I agree that they can be used interchangeably in casual speech because no one really cares. In formal writing, however, everyone should be aware of the difference and when one should be used over the other.