Ditto. I also have the DVD release and GOG's version.

Hmm maybe Mpeg compression (i.e. mp3) wasn't yet fully mature when Torment came out?

Those of us with the retail releases are having to download that patch as well. From the messages in the updater window, I suspect the update servers are just down.

This is somewhat the case. Running a discrepancy report on the data files between a retail patched 1.69 install and the GOG install:

Missing:
xp1patch.bif (7.69MB): I'm not sure this file is used anymore. The 1.69 linux server patch specifically instructs you to delete this file.

Incorrect File Size/Date:
xp2patch.bif (127,609kb): Critical rebuild patches this file to a 359,896kb file that was modified 3 years after the GOG install file (4/29/2005 vs. 5/15/2008)
xp3.bif (463,718kb): Critical rebuild patches this file to a 627,919kb file that was modified 9 hours before the GOG install file (5/15/2008 10:46PM vs. 1:46PM). Weird.

Given the above file sizes, there's your missing ~0.4GB

The culminations of these discrepancies are that users will be missing some textures (partially invisible icons, unexpected silver textures, etc.) and quite possibly game data, but I was able to successfully join a multiplayer server with only the above mentioned texture issues. We have had reports of players with the GOG install crashing on some of the newer tilesets however (Steamworks), so that is likely something missing from the game files. With our automatic updater having a force install option for the Critical Rebuild, these issues were resolved once the patch was re-applied.

The file discrepancy issue has been forwarded to support.

You're all absolutely wrong. It's quite obvious that they digitized a bag of holding to put the files into so they wouldn't take up so much computer space.