>Isn't the linked YouTube video title literally "Season 1, Episode 1"?

Yes and no It's the pilot (and consequently the first[2]) episode "The Gathering", which actually doesn't have an episode number.[0]

The first aired episode was S1E1 "Midnight on the Firing Line".

The former was released as a "TV Movie" even though it was the pilot episode.

[0] http://www.midwinter.com/lurk/countries/us/eplist.html for the episode listings.[1]

[1] Be careful, a wrong click can end up giving you spoilers. :(

[2] I'd note that the pilot episode has significant personnel, prop and make-up differences from the rest of the series.