Pilots train for these events all the time and while it may seem scary to passengers not used to it I doubt there was any actual danger.
I've experienced an aborted takeoff once and a couple of go-arounds. Periods of relative excitement during an otherwise routine situation.
V1 is the critical failure speed at which point the pilots can still safely abort the takeoff. Anything over V1 and the takeoff will still proceed even with just one engine operable.
V1 is the critical engine failure recognition speed or takeoff decision speed. It is the decision speed nominated by the pilot which satisfies all safety rules, and above which the takeoff will continue even if an engine fails. The speed will vary among aircraft types and varies according to factors such as aircraft weight, runway length, wing flap setting, engine thrust used and runway surface contamination.