Here are some words and expressions that appear in the video:
red flag (idiom): a sign of danger, a warning signal
– It can be a red flag if your partner has three different phones and doesn’t explain why.
do something on the spot (idiom): immediately, without delay
– I can’t play the piano on the spot. Instead, I have to look at the music beforehand to get things right.
duty (noun): something that you are expected to do, an action that is required by your job
– You have to carry out your duties at the office if you want to keep your job.