To nuxrl .csf file again

Thanks! Still have problems with the .csf files. I assume the .csf files are movies/flash, or less likely lecture notes of the courses. First, where to check the file permission? second, how to see the head of the file? Third, I downloaded the file and uncompressed them into the folder without any change of the extention. Could it be the problem from the uncompression? Thanks a lot again!