Aircasts are  live streamed, interactive, public broadcasts displayed in a post using Google Hangout audio or video and screen-sharing.
They can be:

• Presentations such as lectures and thesis/dissertation/poster presos;
• Open-ended discussions and ask the expert broadcasts;
• Broadcasts of seminars, workshops, and panel discussions;
• Programmed shows on specific topics
• Reviews of news & events and recorded media such as documentaries, lab experiments, and TED Talks