Some "exclusive" digital versions are ripped from CD-ROMs included with special editions of the audiobook, narrated by Christopher Lee or Sir Derek Jacobi. These PDFs highlight text as the audio plays.
A pirated PDF might render this as:
Support the legacy of the Professor. Buy the eBook, convert it for your tablet, and read it on a rainy afternoon. When you reach the final line— "Thus ended the Children of Húrin; the longest of all the tales of Beleriand" —you will realize that some texts are worth paying for.