I'd just file the discs by Title and not bother with ID's. If they were original discs that had been ripped to HDD that I wanted to keep track of, I would do the same but record the existence of the disc. That could be done by recording a disc type in Media Location. Or, if I wanted to record more information about the discs, I would use a set of custom fields (Date Acquired, Source, Edition, Cost, etc.)
ID's make sense if used as a method of control. That is, each disc acquired is assigned a sequential ID and recorded in the database. The ID is then used to ensure all discs are recorded and all discs recorded exist. The latter is not done by filing the physical discs by ID, but using the database to list all records with an ID according to how they're filed (e.g., by Title within Type—Movie/Series). If the loan system is being used, the list can also indicate which discs are out on loan. The list is then periodically compared to the physical inventory to identify unrecorded and missing discs.
Although not directly supported by PVD, bar codes could be used to control discs. That would depend on the routine of entering a Bar code (and other data that may be looked-up at the same time) using a scanner. A bar code would then indicate the existence of a disc, and serve the same purpose as ID's. The periodic inventory would be taken by scanning all the bar codes, then comparing a list of those with the database.
Which method is used, if any, depends on the number of discs, how important they are, and whether the circumstances warrant some form of control. None require the discs be filed by ID. I would only do that if the discs are only an archive of original media never used for playing or loaning.
