I seem to be having a similar problem to this, I have been advised to simply rename the .264 extension to .avi and it should work. I have done this and some of my video's will play and some won't.
I have tried to upload one of the video's that won't play but the .avi & .264 file extension are not allowed!
I am also trying to create a dvd video of the avi's using adobe premiere pro but the program keeps crashing when exporting the movie at the same point everytime, indicating that there is an issue with the avi. I have tried imputting the avi's that I can view into windows movie maker & nero DVD creator but none of the files will import - I get an error message stating the codec is missing.
Any help with getting the codec or a file converter for this would be gratefully appreciated