Last night on my home machine Youtube stopped working. The box where the flash video plays is black. I came to work today and alas, same thing is happening to me and my co-worker. Both my home machine and my work machine are running Windows 7 64 bit. I tried re-installing adobe flash last night on my home machine and it did not remedy the problem. On all machines that have this issue, youtube videos play fine in chrome, IE, safari, and opera. This seems to be directly related to the last Firefox update that I did.