How to block YouTube app running on Android ?
You Tube App uses the following User-Agent.
User-Agent: com.google.android.youtube/2.4.4(Linux; U; Android 4.0.4; en_US; Micromax A110 Build/IMM76D) gzip
CPL below would block Youtube app via User-Agent.
<Proxy>
request.header.User-Agent="youtube" Deny
Note: request.header.User-Agent object is a Regex entry thus specifying "youtube" would match above User-Agent string