Recording material introducing video into New York libraries (5)
I believe the answer is:
vinyl
'recording material' is the definition.
(material which sound is recorded on)
'introducing video into new york libraries' is the wordplay.
'introducing' indicates taking the first letters.
The first letters of 'video into new york libraries' is 'VINYL'.
(Other definitions for vinyl that I've seen before include "Plastic used for gramophone records" , "Shiny, tough and flexible material used for floor coverings" , "LP material" , "Flexible plastic for flooring (or old records?)" , "LP-making material" .)