What is video startup time?
Video startup time is the time from pressing "play" to the video starting to move.
When a video takes a long time to startup, viewers begin to abandon, and go do something else - maybe even abandoning the site. So it is imperative minimize the amount of time between pressing play and having the video begin playback.
The video tag
In the video tag, you can specify autoplay to esure fast startup. But for videos where a user will press a button to start the video, using the preload attribute can ensure video locally available for playback.
api.video uses adaptive bitrate streaming (ABS). ABS has multiple versions of the videos at different sizes. One way that ABS streams can ensure fast startup is to start the video playback with a lower quality video (240p video is much smaller in KB than a 1080p video). The first few seconds arrive very quickly, the player is able to calculate the network speed, and then subsequent segments are shown at a higher quality. Many video streaming servies use this feature, as the first few seconds of a move or TV shoare are often a black screen anyway.
A robust CDN network ensures that all video segements are stored on the edge of the internet near the viewers - reducing the round trip time for each request. The less time spent in transit is less time in delay for the video to begin on the users' device.