I checked that video, and it already has subtitles. To turn them on, click on the icon that says "CC" - should be 2nd button from left on bottom right corner.
Edit: Although, the transcriptions aren't all that accurate.
Edit #2: Here's what I was able to get.
Nobody know how they build it, still secret. But a lot of people they try to do the (possibly their?) best to give you some information about they did it, but we must say it's secret. The date and the (obscured, but possibly 'dynasty order'?), nobody know it.
Interested in Language