Which technology helps avoid a “blue screen” between changing video sources?

The correct answer is a seamless switcher, which is specifically designed to transition between different video sources without any interruption or visual disruption, such as a "blue screen" appearance. When switching from one video feed to another, a seamless switcher maintains continuity by providing a smooth, professional-looking transition. This technology is especially important in live event productions where maintaining viewer engagement is critical.

The other options do not serve this specific function. Lower thirds are graphics typically used to display information, such as a speaker's name or title, and do not affect the transitioning of video sources. A video encoder is used to convert video signals into a data format suitable for streaming or recording but does not manage the transition between sources. A streaming setup refers to the overall configuration needed for broadcasting content over the internet, which may include various equipment but does not address the seamless switching of video feeds directly. Thus, the seamless switcher is essential for providing a polished viewing experience in digital events where multiple video sources are used.