ETA: libraries have reference material that can only be used in house. This is material is on various subjects. Now, can someone please explain to me, the difference between reference material that can only be used in house, VS say, the TOFT archive which is viewed the same way but in a video format."
I work at the Performing Arts Library at Lincoln Center. (Before I say anything else, I should add that I post here as an individual, not as an official spokesperson for the NYPL.) I'd like to try to answer your question, but I'm not entirely sure I understand it. You're asking what's the difference between reference materials that must be used on site (let's say rare books, or photos), and the videos in the TOFT archive? Is that correct?
Well, one answer would be that the TOFT videos were created under a very specifically worded contract, one that dictates exactly how they are made, where they are stored, the conditions under which they can be viewed and by whom, etc. And everyone involved (including Kerry Butler, by the way) has to sign the contract before the show is taped, and abide by it. But other, non-video materials held by the library are restricted for various reasons. A photo may be under copyright, and a rare book may be restricted simply because it's rare, and/or fragile, and possibly irreplaceable.
I'm not sure if that's what you're asking, but hope this helps.