Hi symphonyofone and welcome to Northern Sounds,
the two instruments you are hearing in Toby's song is a Garritan Stradivari Solo Violin on the left,
and a Garritan Gofriller Cello on the right. Both of these instruments are no longer available for sale.
You are correct,.. the vibrato, vibrato speed, portamento, bow pressure are all features that can be manipulated to produce an exact sound.
GOS2 is a new library that is now in development by Garritan and it will include solo stringed instruments as well as string sections that will produce the sound you desire.
It is still in development and has not yet reached the beta phase.