You can use iChat to Video to PCs that are using the AIM for PC app or have the Trillian App with the Pro Add-on (which costs).
As you list OS 10.7.4 you may find you can find a copy of the Messages Beta (technically it was withdrawn before the release date for Mountain Lion that has the Full version)
Although this Users Tip was written a while ago it may also pay to read it
https://discussions.apple.com/thread/1968438?threadID=1968438 (It is not always as smooth as it should be)
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images." No, Seriously