Not all, but many of the libraries used to have a demo video by Guy Bacos where there was a piano roll view with MIDI notes in sequence and an explanation of which articulation was currently playing.
I found these videos to be extremely useful in not only demo'ing each articulation but how they could be used in a sequence. They were like a "MIDIstration for Dummies" go to reference for inexperienced sample users like myself. As time went on I used them less and less but they're still useful.
Now, the only videos are the trailers. Those are great for exhibition and selling but not so much for informing.
So what happened to Guy's videos?