Nope, either NetSupport Manager / School is top of my list, i not only use it on my network, we have it on all the computers at work (80+PC's) so this is THE tool to use!
they would have to connect to his network and use a packet sniffer, to grab all ip packets and rebuild the stream based on the ip or mac, and then just read the stream for information.
AFAIK they were using a packet sniffer on real husstle. Not straight forward and easy to do but possible. Just do a search on google.
I was wondering if you to able to see their screen or know what they were doing. Two different things.
Remote control will involve installing something on the other PC which means physical or admin access to begin with. A good firewall / anti-spyware will be able to pickup and block any of the remote control support tools listed here. Depends on how technical the other person is.