Found in my game video archives. Originally dated May 19th, 2003 for me. The original filename on my hard drive was `hl2_demo_trailer_full.mov`.
In November 2024, for the 20th anniversary release of Half Life 2, Valve's channel released the direct capture of this video as seen by the E3 2003 audience (minus any narration or audience interaction): https://www.youtube.com/watch?v=CaHtOISsLT4
Some of the content appearing in this demo but cut from the final game can be seen in the Missing Information mod. See http://bit.ly/ML19nX
Since there was some interest about this, here is a write-up in Sharky Extreme about what it was like to view this demo at the time:
http://bit.ly/2oSdORo
