If you've got the website access logging to Kiwi and are trying to filter it within Kiwi Syslog Web Access, then yes you can do this.
1. On the Highlighting tab in Web Access, click on Add New.
2. Event Field would be message text
3. String to Match: whatever string you want to match, IE: cnn.com
4. Then just setup your font preferences check the box next to Preview if you want the whole row to stand out or just the message text field.
5. Click Save.
Edit:
In step3, if you wanted to include all of your example sites, you could use the regex option (don't forget to check the box) and type the following into the field:
redtube/.com|xhamster/.com|pornhub/.com|cnn/.com|bbc/.com
Message was edited by: Acy Forsythe