That happened to me too back when I had NL2. Eventually I just stopped using the in-game recorder and used something else but it never turned out quite as good.
Hi, I am experiencing this problem too. As I don't have the pro version I cannot choose the file format, only resolution and framerate. Does anybody have ideas on how to fix this?
Maybe it is this, maybe it isn't, but for me, I found the videos were not working in Windows Media player. I found opening the same files with quick time player worked fine.