This is part of the in-game hints and tips system that people were talking about when it was first revealed.
Game Start and Game Resume act as just regular game starting/saving/resuming functions.
Digest Game Start acts as the "watch and/or play the parts you want". It basically loads a finished game, and allows you to watch parts of the game or play parts of the game, choosing what part in the game you want to start at or skip to. There is no save function available in this mode, as that would be pointless anyway.
A lot of people seemed to be upset about the in-game hints and tip system without understanding how it would work (the thread about it on these forums was lost with the crash). I'm not sure whether the hints and tips will be available in regular gameplay (Game Start/Game Resume modes) or only in the Digest mode. I'm inclined to think it's not so much hints and tips, as it is playbacks of the previously saved completed sections of the game that are loaded only when you start a game in Digest mode.
Here is the original article that I first read about this: http://nintendo.joystiq.com/2009/01/...d-hint-system/
Note that the invention patent application (linked to in FloYdian's quote) is 469 pages long. It seems to include a lot of stuff that may not be directly related to this aspect of the invention (I was just skipping through some pages and reading the abstract on each page).While the language used in patents is miles above our heads, we feel obligated to try to report on it, because it's apparently Miyamoto's design, and it's potentially quite cool. If we understand correctly, Miyamoto has invented a system that allows players of vastly different skill levels to play adventure games like Zelda, with the ability to skip or receive hints at difficult areas. In addition to accommodating various skill levels, this is designed for people who don't have a lot of time to play games. In effect, it makes the skill level almost totally configurable.
One component of the idea is low-resolution "hint movies" that display the solutions to difficult puzzles at the player's request. In addition, there is a "digest" component that allows players just to watch the game's storyline up to the point of their choosing -- but only after a specified time period (presumably to encourage people to play the game for some number of hours before watching). Finally, there's a DVD-style "chapter" ability that allows players to start the game from a previous "scene" -- rather like the save system in the new Pikmin remake.