Hi,

   Using the below link you can able to block the extension which you need to denied

https://www-secure.symantec.com/connect/downloads/block-access-extension-mp3-mp4-mpg-mpeg-flv 

I want to allow  all other video files except skype video chatting

So you can check the extension of skype video, block only same.

If you want to block any application then try the below attach link.

Actually i am not confirm that skyp application is using the different application source for playing video or not. If it use different source then below doc helpfull to you.

You will need to find out a way to identify chat and video features separately (i.e. specific ports*, specific remote hosts, specific protocols), then use this criteria to block video traffic, either using Firewall or custom IPS policy.

* It seems Skype is not using dedicated ports for video feature (https://support.skype.com/en-us/faq/FA148/Which-ports-need-to-be-open-to-use-Skype), unlike it is for instance with Windows Live Messenger (http://support.microsoft.com/kb/927847/en-us).

Hello,

Did you check these Threads:

https://www-secure.symantec.com/connect/forums/app-blocking-not-working

https://www-secure.symantec.com/connect/forums/sep-blocking-skype-sid-21206-unmanaged-client

You can also, Try these steps - 

Create a Application control Policy in SEPM .

Enter till you find block application and then Edit you have to add the policy in this ways.

c:\program files\skype\phone\*.exe
d:\program files\skype\phone\*.exe
e:\program files\skype\phone\*.exe 

c:\program files\skype\phone\*.bat
d:\program files\skype\phone\*.bat
e:\program files\skype\phone\*.bat

c:\program files\skype\phone\*.com
d:\program files\skype\phone\*.com
d:\program files\skype\phone\*.com

The reason to add the C:\ ,D:\ and E:\ as there may be some user who installs the skype on secondary drive program files

And the reason for all this scenario is that even if user change the name of Skype to other like in Test or Byepass and this policy will Block the Skype.

Hope that helps!!

Thanks mithun. I will check and get back you