I found the video cached in \local settings\temp folder as revealed by
Video Cache Viewer (the guy deserves a hero's medal for all the utilities he's come up with). You can clearly the filesize increase as the video caches. Trouble is I can't copy the thing it's locked by Plugin Container (flash player), unlock it and it's instantly deleted.... Video Cache Viewer's copy function only copies the first 25mb of it (it was up to 350mb+ in the cache)