For over 7 years I was developing in .Net. Recently I was researching Silverligh and what I saw is frankly disappointing. Not even this video works as expected in Firefox 20. It ignores the pause button, the board disappears when trying to click something on that, user cannot go forward on the video and it is prompted at random to accept full screen mode (if choosing "No" then the program do just the opposite and switches to full screen mode). That's just an example. I've tried to run a game made in Silverlight, it uses a lot of resources and sometimes my browser and even Windows get frozen and I have to turn electricity off to restart the PC (ctrl+alt+del also is ignored). All buggy and crapy!