These are official videos. There are also coach's documents available you can get from TeamUSA, or from your country's Olympic site. The coach's document specifies competition-specific details, such as timing, height of kicks, placement of feet, and other nuances that are completely irrelevant when you need the forms for advancement or local competitions.
The coach's document is updated periodically, if I get a chance to find it, I'll update my answer. But this should get you going.
You are right to ask for official references, there are some people out there with some very strange ideas about what's going on in poomsae, even by high ranking instructors.
This set is produced by Kukkiwon, and features none other than Dr Lee Kyu-Hyung, and there should be no other source you should get your instructor from.
This set DOES come from a DVD set, and I do not know of its legality to be on YouTube, though they've been up for a few years.
BTW, there are some videos out there with these same videos, and they contain English subtitles. You may find them helpful when you get to the instruction parts. However, you can figure things out a little bit just by watching, even if you can't understand Korean.
EDIT: This is the coach's document I mentioned, and comes directly from World Taekwondo.
WT Poomsae Competition Rules & Interpretation (March 19, 2014)
If this document gets stale, you might be able to find a link here.
Taeguek Il Jang
Taeguek Ee Jang
Taeguek Sam Jang
Taeguek Sa Jang
Taeguek Oh Jang
Taeguek Yuk Jang
Taeguek Chil Jang
Taeguek Pal Jang