Just curious about this. Frequently, a lot of gameplay videos from big studios have small subtitled text at the lower part of the screen, reading something like:

• Pre-Alpha Gameplay -- Footage not Final
• Game Footage not Final
• Pre-Alpha, Game here is not final

Is there some sort of reason they do this? Is there some sort of legal ramification that they need to go through by adding this? I have especially seen some gameplay vids whose titles are "Alpha x.x.x", yet still, in the video itself, it always something like "footage not final, game may change".