It sounds like a collectors item, especially if there are no (or few) other copies of that same take.  Are you certain the record is made of glass, as opposed to something else that had a glassy finish and glasslike fragility?

The record in question is most probably glass-based, i.e. a glass disc that was coated with acetate for recording purposes. These were introduced during World War II, due to metal shortages and needs, and were primarily in use during the 1943-1946 time frame (although some may have been used in later years, just to use up the existing supply). These records worked just like the usual acetate records, except that "regular" acetates, as we know them, were aluminum-based, and here the glass disc replaced the aluminum disc... but they were both coated with the same type of acetate material, into which the grooves were cut.
The recording in question could be an a rehearsal, or simply a copy of something recorded from another disc.  A mention of a "title", or the product Bing was singing about, could help identify and date this (or at least date the original recording or broadcast, since this could be a copy). ... Something like the singing Philco commercial that Bing did with Jolson...