While the user is waiting, the website runs background scripts that use system resources to 'watch' YouTube videos without displaying them on the screen. In fact, the timer continues to reset to 59 sec - it never reaches 0. To receive the gift, users must (once again) wait for the timer to reach zero. Malware security researcher, Lawrence Abrams, has recently discovered an 'Amazon Gift Card' scam site that contains a countdown timer.
This is done to misuse system resources and perform various tasks, such as mining cryptocurrency (typically, Monero).
Some sites attempt to trick users into staying on the malicious site as long as possible (e.g., the user must wait for a countdown timer to reach zero before starting the survey). In most cases, they are asked to complete a survey or provide registration details (personal information including email addresses, which are used to send the gift card). To receive the card, however, users must perform various tasks. All essentially state that the user is a lucky visitor and has the chance to win a gift card (typically equivalent to $1000) from the Amazon e-shop. There is a huge variety of 'Amazon Gift Card' type scams (e.g., You Are Today's Lucky Visitor).