Trademark is not ownership of the word. Anyone and everyone can use the word "Portal" to speak about the game, its mods, its lore, fan content, likes and subscribes, etc.

The video was originally titled in the already common pattern across all industries in the media: "Work title: Work subtitle - Official Announcement". It's honestly not hard to parse, and it does not constitute in itself any judgment on whether it's Valve's Portal or the Portal of anyone else who can and is allowed to use the name (think eg.: I write my college thesis and announce it as "Portal: Why the Game is Good - Official Announcement").

I do be fair and mention I come from the Pokémon fandom, where (until the series went into Yearly Crunch) the amount of fan content more than 7x-ed the amount of "official media" so one learns to parse announcements and titles faster. I guess I'm trained by a different internet than yours. However I don't get why you think I'm somehow "flinging insults", but I guess that just strengthens my point that elementary education should be revisited.