Polybore pieced together this solution from a number of existing sources which each on their own did not supply all the information. Polybore has amalgamated the information into an easy 4 step process which you can skip to at the end of the post (Method). For all the information read on.
Piecing together the information.
Polybore’s dual monitor set up is a monitor and a TV connected to their home theatre PC. One niggle that has been bothering polybore for months is that when streaming flash media (like the BBC iplayer) in full screen mode on the TV any click activity on the monitor and the flash media on the TV would exit full screen.
After periodically searching for a fix for this polybore has finally found a solution at least for Chrome and Firefox.
Credit where credit is due and thanks to orlandmedia for setting polybore in the right track. http://www.orlandmedia.com/blog/adobe-flash/fullscreen-flash-player-on-dual-monitors/
Orlandmedia links to the fix over at my.opera.com http://my.opera.com/d.i.z./blog/2009/04/22/watch-fullscreen-flash-while-working-on-another-screen
From there you can download a file called NPSWF32.zip containing NPSWF32.dll which is a modified flash plugin (version 10.0.32.18). Now we are making progress but the post does not include instructions on how to install this modified plugin. An anonymous comment on the post mentioned a YouTube video with a fix so polybore searched YouTube and found this video by dbosst http://www.youtube.com/user/dbosst
The video details how to modify the flash plugin yourself with a hex editor but we don’t need to do this because we already have the modified flash plugin that we downloaded earlier from my.opera.com All we need to know now is where to put the modified NPSWF32.dll and now we do thanks to this video. It goes in c:\windows\system32\macromed\flash\npswf32.dll
Having downloaded the modified flash plugin from http://my.opera.com/d.i.z./blog/2009/04/22/watch-fullscreen-flash-while-working-on-another-screen
1- navigate to the folder c:\windows\system32\macromed\flash\
2- rename the existing npswf32.dll to npswf32old.dll (you don’t need to do this but it is good practise in case you want to revert to the original plugin).
3- copy the new modified file that was downloaded from my.opera.com to the folder c:\windows\system32\macromed\flash\
4- Close all browsers and restart them.
Having tested it this works a treat with Firefox and Chrome. It does not work with IE8 and polybore was unable to test with opera (but it should work if you use the alternative folder detailed in the video).
Now we can watch the BBC iplayer, YouTube or any flash streaming media on the TV while at the same time using the monitor for other stuff without interrupting the video.