With Firefox, whenever I browse to a page where there's a video playing within the browser, the video will fail to load, and my browser will freeze as soon as I try to close that window. I didn't have this issue before my hard drive went kerplunk and I re-installed Firefox. I do use K-Lite, but I tried uninstalling that and apparently that's not the issue. I've used K-Lite forever, anyway, I don't know why it would go all screwy now.
You could try the Media Player Connectivity Extension for Firefox. It basically doesn't try to load a video until you decide how you want it done. It's done wonders for me.
