Where do GDC trailers come from?

For many years I knew of GDC only as a prefix that some trailers for games had. It's only as I actually pay more attention to GDC and the nature of it that made me wonder. Where do GDC trailers actually get shown at GDC?

So GDC is ostensibly where the developers go for seminars, networking and the like. Obviously in practice there is a lot of press there but despite that, as far as I can tell, GDC doesn't really make a lot of concessions for press which, unless I am mistaken is part of why Giant Bomb doesn't go there. It seems like there isn't really a natural place for these trailers to be shown.

I've been looking at what's on this year and while deeply interesting none of it looks like the sort of thing where you can just say "thanks for listening, here's our new trailer for MGS" without it being extremely jarring. That's my confusion I guess. At E3 the new trailers come as part of the conferences but as far as I can tell devs don't have the same sort of platform at GDC.

Maybe I'm over-thinking this and GDC trailers are just trailers that get passed around through regular PR channels that just happen on the dates of GDC. I feel I must be missing something and I'm sure someone in the collective Giant Bombsciousness knows the answer or holds some sort of insight.

Probably panels; it doesn't happen very often but there have been a couple of bigger game reveals at GDC, but I think they are encouraged to not do stuff like that. Other than that its probably at people's booths or just released to the internet during the time of GDC.

Most of them are just released at the same time as GDC but won't actually be shown in any capacity at the show itself - possibly at the game's booth but a lot of games you'll see trailers for won't even have booths.

Also, keep in mind that there are a lot of smaller events occurring around the edges of GDC where press might be more involved. Additionally, with a large portion of the games media located in the San Francisco area, a lot of the more established developers take the trip to GDC as an opportunity to show off their new projects directly to press outlets.