How to do video chat and swiftly switch voices and faces?

There will be two things to keep in mind: The software application which allows you to do video chat, and the assisting tool for changing faces and voices while video chatting.

Most popular video chat software:
Choosing the appropriate video chat software makes huge effects on the quality of your webcam chat image. So here are some suggestions:

Yahoo Messenger: is a totally free instant messaging computer-based application which is provided by Yahoo! It is not only a powerful instant messenger, but is also an all-in-one voice chat, webcam hosting, emailing, gaming, picture and file sharing, etc. tool which makes it the most popular IM application of online users. Users can send a webcam view invitation to as many friends as they want. The quality of the webcam image can be affected by the type and speed of the connection; here faster is better.
OS supported: Windows, Mac OS X, and Linux.

Skype: is one of the most popular VoIP software due to its user-friendly, feature-rich options: make voice calls over the internet (PC-to-PC, PC-to-Phone, Phone-to-PC), text message, video conference, file transfer, and the latest update, Skype 4.0, includes a sharing screen. The video and audio quality exceeds expectations: clear audio, clear and smooth video with no lag in the connection; plus, the streaming won't take up all of your Internet bandwidth. While this is a powerful program, at this time, there's no official support from Skype for multi-peer video conferencing.
OS supported: Windows, Mac OS X, and Linux.

Additional tool to change voices and faces:
All Windows VoIP and IM applications (like Skype or Yahoo Messenger above) will receive a big boost in their video chat functionality by using AV WebCam Morpher software to enhance the voice and webcam image.

AV WebCam Morpher (available at www.audio4fun.com) is worth a try for its real-time audio and video enhancing features and background changing ability. Users can create fun webcam images and control them in real time to entertain and amaze their chat-mates.