I've been trying to watch Netflix movies using Firefox after upgrading to Lion. Each time I go to the Netflix website, Silverlight fails, and the suggested fix from Netflix is to quit Firefox and delete my Silverlight.plugin file from the 'Internet Plug-Ins' folder. Then, when I go back to the Netflix website, I am prompted to download/install Silverlight. Then it works. I've tried to use Netflix twice since my Lion install, and had to do this both times.
This is only one of the many many dissappointing failures/crashes that has plagued my Macbook since installing on Thursday.
Also have a problem with Lion and Netflix on my MacPro. In Safari after choosing a selection, video goes to black screen and nothing happens. Sometimes I get a plug-in error notice. I re-installed Sliverlight, still doesn't work for Safari. However, Netflix works perfect when using Chrome. For me at least, it seems that the main issue is Netflix+Safari+Lion.