The DFLW lobby changed and this required an update. The reason the update is big is because it is capable of updating a game directly from the original CD (hence why all the files needed are included and the size of the download).
The "new" binaries are exactly the same as the old and the only difference is you a new startup.htm file to point to the updated lobby.
Honestly, it is kind of lame that they did it that way. Would have been simplier to just have the lobby server redirect to the new page but go figure
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