On Tue, 24 Dec 2013 01:42:24 -0800, mike wrote:

I never learned whether teamviewer sends info thru their servers
or just uses them to set up a direct connection. That could make
a big difference for local use.

PDF:

"TeamViewer Sessions
Creation of a Session and Types of Connections
When establishing a session, TeamViewer determines the optimal type of
connection. After the handshake through our master servers, in 70% of
the cases a direct connection via UDP or TCP is established (even
behind standard gateways, NATs and firewalls). The rest of the
connections are routed through our highly redundant router network via
TCP or http-tunnelling. You do not have to open any ports in order to
work with TeamViewer! As later described in the paragraph "Encryption
and Authentication" even we as the operators of the
routing servers cannot read the encrypted data traffic.

Encryption and Authentication
TeamViewer works with a complete encryption based on RSA
public/private key exchange and AES (256Bit) session encoding. This
technology is used in a comparable form for https/SSL and can be
considered completely safe by today's standards. As the private key
never leaves the client computer, it is ensured by this procedure that
interconnected computers - including the TeamViewer routing servers -
cannot decipher the data stream. Each TeamViewer client has already
implemented the public key of the master cluster and can thus
encrypt messages from the masters and check its signature
respectively. The PKI (Public Key Infrastructure) effectively prevents
"Man-in-the-middle-attacks". Despite the encryption the password is
never sent directly but only through a challenge-response procedure
and is only saved on the local computer.

http://www.teamviewer.com/en/res/pdf/TeamViewer-Security-Statement-en.pdf