I found time to do some research in my DVD and BluRay collection, to find titles where the color keys are used.
I was sure I saw some DVDs that were making use of the color keys, but I could not find any among the ones I tried. Eventually I gave up, it's possible such DVDs exist, but I lost patience at some point and did not look further.
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However, I found a lot of BluRays that make use of the color keys, I just never payed any attention to them.
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Pretty much all Paramount BluRays have this kind of functionality where if you press the Green button, it saves a bookmark for you. On all Star Trek Movies BluRays (but not only, it's the same type of menu with the same kind of functionality on the Super 8 BluRay for instance) you can see the list of saved bookmarks if you go from the Main menu -> Scenes submenu -> Bookmarks list. I've attached two screenshots from the Star Trek - The Motion Picture BluRay (EU edition) of the Main menu and of the Scene Bookmarks submenu to show how it looks like. I could not make a mini-BluRay version of this movie however, its file structure is very complex and the size of something that would work would be too great.
I did make a mini-BluRay version of the first disc of the movie I mentioned, "The Celebration". This one has a Timeline submenu that can be entered from the Main menu, where you can move across the timeline and edit bookmarks. I added a screenshot below of this Timeline submenu, where you can see there is a legend to explain which color buttons can be used for which actions. The mini-disc is here:
https://files.catbox.moe/rz8t0d.7zYou might be left with a feeling these color buttons are only used to set bookmarks after reading the above. However, I discovered these color buttons are sometimes used for other purposes as well (I just never really payed them attention before
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). On the Star Trek The Original Series BluRays, for instance, they are used as shortcuts for accessing menu items either in the Main menu or in the Popup menu. I added some screenshots of the Main menu and Popup menu below. See those red/green/yellow/blue balls in the menus? They're not just for aesthetics (resembling buttons on the 60's Enterprise console), they are hints for which color buttons to press to select a menu. Again, the file structure of the BluRay is very complex, I'm not sure I can make one of a small size for testing purposes. I've only attached some screenshots for you to see.