How do I send and receive instant messages during a video call for Skype for Mac OS X?
To send or receive an instant message while on a video call, click the Share button and select Instant Message.
You can then send and receive instant messages just as you would normally do during a chat. Simply type your message in the text box and press Return on your keyboard.
When you receive an IM or a file during a voice or video call, the icon bounces and a red dot appears indicating an event .