What is the primary characteristic of a webcast?

The primary characteristic of a webcast is that it involves the transmission of video media files over the Internet, which allows a wide audience to access the content in real time or on-demand. Webcasts can typically include a combination of audio and video elements, providing a more engaging experience for viewers compared to just audio or text alone. This method is especially effective for reaching large audiences, as it utilizes streaming technology to deliver content seamlessly over the web.

In contrast, the other options focus on narrower definitions or formats. A live audio transmission only does not encompass video elements or the broader capabilities of a webcast. A pre-recorded audio presentation lacks the real-time engagement and visual component that webcasts provide, while an interactive video conferencing tool is focused on two-way communication among participants rather than a broader audience viewership typically associated with webcasts. Therefore, the most accurate representation of a webcast aligns with its definition as a transmission of video media over the Internet.