How to implement custom ContentProvider for video in BLOBs

In my app videos are stored as series of encrypted SQLite BLOBs.

In order to play video directly from those SQLite I need to write my own custom ContentProvider. I know how to implement basic ContentProvider over SQL queries, but in this case I have no idea how to do this.

How VideoView.setVideoURI() utilize supplied URI? Either it read is as Cursor or ParcelFileDescriptor or somehow as kind of stream?

Any ideas, clues, hints?