THE FOLLOWING is a truncated video below. it's a lot better watching the whole DVD but if time or money prohibits, then the video below is enough. The video below is "Christ Alone":

https://www.youtube.com/watch?v=ocHm18wUAGU&t=1781s

Why starting us 1781 seconds in?

I don't think that's what it means. It's simply part of the link address

YouTube video links that end in &t= {insert number here] s causes the video to begin playing [insert number here] seconds in. For example, if the link ended with &t=60s, then I would start 60 seconds into the video.

I see; thank you for explaining that. As for your question, I don't know why.