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.
However, I found a lot of BluRays that make use of the color keys, I just never payed any attention to them.
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
). 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.