Can we use NBAR on the gateway router to prevent internal users from watching video streams from any video web site (like Youtube.com)?
Yes, NBAR can be used to apply application based filters such as blocking youtube.com traffic. To accomplish this we can categorize traffic based on the HTTP hostname. Next we will create a policy-map that matches the youtube.com class and drops the traffic. Lastly the policy is applied outbound to the Internet. Syntax-wise this would read:
class-map match-all YOUTUBE
match protocol http host "*youtube.com*"
description TO INTERNET
service-policy output DROP_YOUTUBE
NBAR for HTTP can also be used to match based on URL string or IANA MIME type. For more information see: