I run into similar situations whenever I restart my browser. All of the YouTube tabs I had open from before start playing simultaneously (at any given time I often have some tabs with videos paused, ready for me to watch later). It's quite distracting and takes some effort to find and stop them all.
I think a good solution for both of our problems would be to not load any of the Flash content in a particular tab if the tab hasn't received focus since the application was restarted. Once I open that tab, the plugin can load at that point and then the video can start playing.