The .ldb file is generated when MediaShout uses a database. It is an offshoot of Microsoft Access's method of controlling databases (and records). It tells the system when & where users are using records. This allows us to have multiple users accessing the same file simultaneously and not "bump" or conflict. With the Bible databases, it is not needed (but still there).
The ldb file should automatically be removed within a few seconds after MediaShout is closed. If MediaShout is already closed and the file is still there, you can safely delete it.