App Not Installing (corrupt package) but Reported Successful

I got prompted on my RN516 to upgrade to 6.1.8 today. Checked release notes and it looked pretty innocuous, so I went for it. Later, I was working on installing RC1 for DVBLink v5 and ran into a serious problem, from /var/log/readynasd/install_debpkg.log:

    START(/tmp/dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb): Wed May 14 15:48:14 PDT 2014
    Hit http://mirrors.kernel.org wheezy Release.gpg
    Hit http://mirrors.kernel.org wheezy Release
    Hit http://mirrors.kernel.org wheezy/main amd64 Packages
    Hit http://apt.readynas.com 6.1.8 Release.gpg
    Hit http://apt.readynas.com 6.1.8 Release
    Hit http://apt.readynas.com 6.1.8/updates amd64 Packages
    Hit http://apt.readynas.com 6.1.8/apps amd64 Packages
    Hit http://apt.readynas.com 6.1.8/main amd64 Packages
    Reading package lists...
     new debian package, version 2.0.
     size 6557666 bytes: control archive=17313 bytes.
         150 bytes,     6 lines      changelog           
        1432 bytes,    34 lines      control             
        3288 bytes,    80 lines      copyright           
       48059 bytes,   477 lines      md5sums             
        3090 bytes,    87 lines   *  postinst             #!/bin/sh
        1100 bytes,    37 lines   *  postrm               #!/bin/sh
          18 bytes,     3 lines   *  preinst              #!/bin/sh
         952 bytes,    34 lines   *  prerm                #!/bin/sh
     Package: dvblink-tv-server
     Version: 5.0.0
     Architecture: amd64
     Maintainer: DVBLogic <info@dvblogic.com>
     Depends: readynasos (>=6.1.3)
     Depends: readynasos (>=6.1.3)
    Found 1 dependants
    pkg[1/1]= readynasos >=6.1.3
    Chking dependencies..
    pkg[1/1]= readynasos >=6.1.3
    Depenency  readynasos >=6.1.3 met
     Section: video
     Priority: optional
     Homepage: http://www.dvblogic.com
     Description: DVBLink TV Server
      TV solutions for your NAS and Windows PC!
      Our range of DVBLink products for NAS and for Windows based PC's offers
      everything you need to enjoy your favorite Satellite (DVB-S/S2), Cable
      (DVB-C and QAM), Terrestrial (DVB-T/T2 and ATSC) and IPTV
      channels and recordings within your home network and on the go!
      .
         - Record your favorite TV programs in original quality directly to a
      hard disk of your NAS or your PC
         - Watch live and recorded TV on your Windows, Mac or Linux PC with DVBLink
      XBMC client!
         - Watch live and recorded TV programs in Windows Media Center
         - Watch live and recorded TV throughout your house on DLNA devices such as
      TV's, PS3's etc.
         - Watch live and recorded TV programs on Boxee Box using DVBLink Boxee
      Client. No running PC is needed!
         - Watch your live TV programs on your iPhone, iPad, Android device or
      Windows Mobile phone
         - Never miss your favorite programs again, browse the EPG and set
      recordings while you are on the go!
         - Get the program information you want - Microsoft EPG (Electronic Program
      Guide) information, EPG from the stream, your favorite xmltv, Digiguide,
      EpgData.com, IceTV or TimeFor.TV TV listings
     
     
     
    fv-dpkginstall.awk: success
    Success install dependencies for /tmp/dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb
    (Reading database ... 35458 files and directories currently installed.)
    Unpacking dvblink-tv-server (from .../dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb) ...
    dpkg-deb (subprocess): cannot copy archive member from '/tmp/dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb' to decompressor pipe: unexpected end of file or stream
    dpkg-deb: error: subprocess paste returned error exit status 2
    dpkg: error processing /tmp/dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb (--install):
     cannot copy extracted data for './apps/dvblink-tv-server/common/ffmpeg/ffmpeg' to '/apps/dvblink-tv-server/common/ffmpeg/ffmpeg.dpkg-new': unexpected end of file or stream
    Errors were encountered while processing:
     /tmp/dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb
    DONE(0): Wed May 14 15:48:17 PDT 2014
    spooler returns spool_status=0 outbuf=(null) errbuf=(null) is_localapp=1 name=dvblink-server-netgear-linux-r6-x86_64-5.0.0.deb pkgname=dvblink-tv-server

Worse, when I went back to install the previously installed and working v4 it failed with precisely the same messages. :( Downloading 6.1.7 now to revert and attempt again on that OS release. Not sure what changed, but it seems to be causing some headaches.