Comment 3 for bug 181765

I can confirm this - Just attempted to install this via Firefox, which loaded the plugin installer. Firefox will continuously prompt you to install Flash, but the installer will state that it is already installed.

When attempting to do so from the command line, the following output is observed.

steev@setsuka:~$ sudo apt-get install flashplugin-nonfree
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
  konqueror-nsplugins msttcorefonts ttf-xfree86-nonfree xfs
The following NEW packages will be installed:
  flashplugin-nonfree
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/18.1kB of archives.
After unpacking 160kB of additional disk space will be used.
Preconfiguring packages ...
Selecting previously deselected package flashplugin-nonfree.
(Reading database ... 91075 files and directories currently installed.)
Unpacking flashplugin-nonfree (from .../flashplugin-nonfree_9.0.48.0.2+really0ubuntu12_i386.deb) ...
Setting up flashplugin-nonfree (9.0.48.0.2+really0ubuntu12) ...
Downloading...
--17:49:14-- http://fpdownload.macromedia.com/get/flashplayer/current/install_flash_player_9_linux.tar.gz
           => `./install_flash_player_9_linux.tar.gz'
Resolving fpdownload.macromedia.com... 72.246.86.70
Connecting to fpdownload.macromedia.com|72.246.86.70|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3,036,127 (2.9M) [application/x-gzip]

    0K .......... .......... .......... .......... .......... 1% 155.66 KB/s
   50K .......... .......... .......... .......... .......... 3% 254.11 KB/s
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 1400K .......... .......... .......... .......... .......... 48% 1.46 MB/s
 1450K .......... .......... .......... .......... .......... 50% 841.84 KB/s
 1500K .......... .......... .......... .......... .......... 52% 761.67 KB/s
 1550K .......... .......... .......... .......... .......... 53% 889.44 KB/s
 1600K .......... .......... .......... .......... .......... 55% 839.31 KB/s
 1650K .......... .......... .......... .......... .......... 57% 1.04 MB/s
 1700K .......... .......... .......... .......... .......... 59% 1.41 MB/s
 1750K .......... .......... .......... .......... .......... 60% 930.92 KB/s
 1800K .......... .......... .......... .......... .......... 62% 1.09 MB/s
 1850K .......... .......... .......... .......... .......... 64% 1.64 MB/s
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 1950K .......... .......... .......... .......... .......... 67% 1.09 MB/s
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 2050K .......... .......... .......... .......... .......... 70% 1.68 MB/s
 2100K .......... .......... .......... .......... .......... 72% 808.51 KB/s
 2150K .......... .......... .......... .......... .......... 74% 996.20 KB/s
 2200K .......... .......... .......... .......... .......... 75% 909.25 KB/s
 2250K .......... .......... .......... .......... .......... 77% 1.74 MB/s
 2300K .......... .......... .......... .......... .......... 79% 958.02 KB/s
 2350K .......... .......... .......... .......... .......... 80% 898.26 KB/s
 2400K .......... .......... .......... .......... .......... 82% 775.22 KB/s
 2450K .......... .......... .......... .......... .......... 84% 3.03 MB/s
 2500K .......... .......... .......... .......... .......... 86% 755.48 KB/s
 2550K .......... .......... .......... .......... .......... 87% 795.67 KB/s
 2600K .......... .......... .......... .......... .......... 89% 853.74 KB/s
 2650K .......... .......... .......... .......... .......... 91% 733.63 KB/s
 2700K .......... .......... .......... .......... .......... 92% 798.97 KB/s
 2750K .......... .......... .......... .......... .......... 94% 816.58 KB/s
 2800K .......... .......... .......... .......... .......... 96% 812.61 KB/s
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 2900K .......... .......... .......... .......... .......... 99% 1.12 MB/s
 2950K .......... .... 100% 818.39 KB/s

17:49:18 (757.18 KB/s) - `./install_flash_player_9_linux.tar.gz' saved [3036127/3036127]

Download done.
md5sum mismatch install_flash_player_9_linux.tar.gz
The Flash plugin is NOT installed.