Singlish word: Kiasu (Hokkien dialect) - 怕输
To be afraid to lose out / to be on the losing end - usually used to describe someone after he has taken an action that shows he is afraid of losing out.
In the video, Johnson was kiasu because he didn't wait for Elyn and Jess and he went ahead to collect and drink the spring water long before them.
For Jess and her ice-cream in the video, rather than just picking one flavour, she ordered a cone with ALL six flavours - she was afraid she would lose out if she didn't try all the flavours.
You have been standing in the queue for 3 hours just to get the free gift? You're really kiasu.
You bought 100 rolls of toilet paper because they were on sale? You're really kiasu