No, numerologists of the Interwebs, this is not confirmation of Half-Life 2: Episode 3. It's a compilation of interviews given and questions taken by Valve boss Gabe Newell in the decade since the infamous finale to the Half-Life trilogy was first announced.
That happened May 24, 2006. Valve and Newell were, for a time, very happy to discuss plans for Half-Life 2: Episode 3. Ten years ago, Valve was even happy to give the game a launch window — "by Christmas 2007." Perhaps not coincidentally, 2008 is when Newell starts clamming up about it.
The posture changes from "we're still working on it, of course," to a very strict "we have nothing to say about Half-Life." At least in this video's chronology, the last time Newell was on camera saying the game was even still in development was with Geoff Keighley in 2009. From there: zip.
One of the biggest indicators that Half-Life 2: Episode 3 isn't happening, aside from the fact the thing isn't, you know, out, is that the developer who wrote all of the games preceding it retired in January. Marc Laidlaw called it a career after 18 years with Valve, beginning with 1998's Half-Life.
The last time anyone in any position of authority said anything remotely forward-looking about Episode 3 was March 2015, when HTC's chairwoman namedropped the franchise in an interview about the Vive, the VR headset HTC and Valve co-developed that launched earlier this month. That was very, very quickly walked back.
Days later, Newell gave an interview with Keighley in which, without mentioning Half-Life 2: Episode 3, said: "The only reason we'd go back and do like a super classic kind of product is if a whole bunch of people just internally at Valve said they wanted to do it and had a reasonable explanation for why." Apparently, a Half-Life movie is more of a sure thing. According to J.J. Abrams, not Valve, of course.
Polygon has not reached out to Valve for comment and will not update this story when none is received.