It sounds like the files are not what their extensions say they are.
The following assumes you are a Windows user...
Try this (simple method):
~ Go to a command shell "Start>Run(or search all files), type in
cmd
~ At the command prompt change folder to wherever the .asf & .avi files are located...
Example: cd C:\pictures\friends
Look at the file contents using the more command
Example of using the more command (this is also known as dumping) against one of my .avi files:
C:\Users\peter\Dropbox>
more be-200.avi
RIFF┤¢╗
AVI LIST~"
hdrlavih8
@£
Copy the first 10 lines and paste them here so we can take a look at them...
Try this (complex method):
~ Download Microsofts strings command and
unzip it to the same folder you have these .asf & .avi files in.
~ Go to a command shell, click on
Start>Run(or Search all files), type in
cmd
~ Change folder to wherever the .asf & .avi files are located at the command prompt:
Example: cd C:\pictures\friends
~ Execute the strings command with one of the unknown files
Example of using the stings command against one of my .avi files:
C:\Users\peter\Dropbox\DTWallpaper>C:\Users\peter\ Dropbox\SysInternals\strings be-200.avi |more
Strings v2.51
Copyright (C) 1999-2013 Mark Russinovich
Sysinternals -
www.sysinternals.com
RIFF
AVI LIST~"
hdrlavih8
LIST
strlstrh8
vidsdivx
strf(
DX50
JUNK
LIST
strlstrh8
auds
strf
JUNK
LIST
odmldmlh
JUNKf
Copy the first 10 lines and paste them here so we can take a look at them...