What does it mean by "youngsters are killing everything" here?
This answer requires a bit of an explanation about the conflict between the younger generations and baby boomers (people in their 50s to 70s). "Youngsters are killing everything" is meant in an ironic way - baby boomers are famous for complaining that Millennials and Generation Z are killing (ending) many industries, such as those seen in the video (cereal, bar soap, mayonnaise, etc.), by no longer using these products. Thus, the speaker is referring to this conflict by saying that "us youngsters who are killing everything [or supposedly ending many industries] are driving the reselling trend," which is actually creating a new industry.