There is only one worldwide version of Fallout 3; the Australian version is identical to the US copy. The item Morphine was renamed Med-X to pass through the Australian Classfication Board. The name change was also applied to all other international versions of the game.

A better example would be a game like L4D2. However that should be perfectly fine. Although video games lack an R18+ rating in Australia, such a rating exists for television and film. Therefore, a video of a RC computer game should be fine (as long as it is within the constraints of the R18+ rating for film).

I think it's unlikely that YouTube would a host a video on crime instruction that would be severe enough to be considered RC. I may be wrong. Perhaps someone could try uploading a euthanasia how-to video on YouTube describing explicitly the steps involved in performing euthanasia - the drugs required, how to obtain and smuggle such drugs through Australian customs, and the dosage required. I suspect that YouTube would probably take it down.