I had success using FFMPEG to convert the .264 file into an .avi file. If you install FFMPEG onto your C: drive, then running the following command line should convert it:
C:/FFMPEG/bin/ffmpeg -f h264 -i ORIGINAL_FILE_FULL_PATH NEW_FILE_FULL_PATH.avi
For example if the video you want to convert is at C:/Users/..../originalName.264, that's what you would put in for ORIGINAL_FILE_FULL_PATH, and if you wanted to convert it to the same place, your final instruction would be:
C:/FFMPEG/bin/ffmpeg -f h264 -i C:/Users/..../originalName.264 C:/Users/..../ConvertedName.avi
Note that for slashes you need to use '/’ instead of '\’. Let me know if this helps!