Three seconds, three tactics
'Say something or show something in the first three seconds.'
Most viewers decide inside two or three seconds, which means the best material in the video is worthless if it sits behind a slow opening. Three tactics do the work: shock them visually, ask a question, or withhold something so curiosity carries them forward - the gadget reel that does not reveal what the device is until later being the worked example. After the hook, retention is an editing problem: quick cuts and constant visual movement so no moment offers a natural exit. And rewatches, which curiosity hooks and fast cuts produce, are described as a strong signal back to the platform.
The same discipline as the YouTube hook, compressed from five seconds to three.
Say something or show something in the first three seconds. That leaves people with no other choice but to keep watching your video.