To steal the words of a wise person, VideoSift addiction is...

...akin to poker machine addiction, as it uses a similar system of intermittent rewards for behaviour, as first expounded by psychologist BF Skinner. The idea is that if you perform action X you can expect reward Y, and this can be mildly conditioning, or "addictive". However, Skinner discovered that this action-reward link embeds itself more firmly in your brain if the reward doesn't come every time, but more or less randomly, as long as it only comes if you perform the prescribed action.

Thus, a poker machine addict will keep hitting the "play again" button like a trained rat so long as the flashing animations and jangly sounds of a win only occur every now & then.