From Second Life Wiki
NHC posted the following instructions to their user group concerning Flash support in viewers. Presumably these instructions would work for other media devices that require Flash support in the viewer:
If you like the old UI like SL or Emerald 1.23, the Emerald viewer 2270 (1.4.0) is a good option for you because it has the same UI of these old Viewers, but it has support for flash player and the Emerald feautures that we love.
PS.: All the steps below apply to Snowglobe Viewer too.
1) First download and INSTALL one of the options below:
Windows: http://hotfile.com/dl/54788731/41ecdcb/install_flash_player.exe.html MAC OS X 10.4 - 10.6: http://hotfile.com/dl/54789700/04c8f0f/install_flash_player_osx_ub.dmg.html MAC OS X 10.1 - 10.3: http://hotfile.com/dl/54789290/48fe8d4/install_flash_player_9.dmg.html Linux: http://hotfile.com/dl/54789035/d51db32/install_flash_player_10_linux.tar.gz.html
2) UNINSTALL your Emerald Viewer, including the Emerald Folder and Subfolders.
3) Choose one of the options below, donwload it and DO NOT INSTALL:
Windows: http://modularsystems.sl/box/Emerald_Viewer_18.104.22.1680.exe OS X Intel: http://modularsystems.sl/box/Emerald_Viewer_2270_Intel_Beta.dmg OS X PPC: http://modularsystems.sl/box/Emerald_Viewer_2270_PPC_Beta.dmg Linux: http://modularsystems.sl/box/EmeraldViewer-i686-22.214.171.1240.tar.bz2
4) RESTART your computer.
5) INSTALL the new Emerald Viewer.