It was only shown to the audience in Hall H and was never made available publicly. From most reports, it was fairly similar to the trailer this week except a bit more expanded, and opened with the full aforementioned "Try to Lift Mjolnir" scene before Ultron shambles in and starts his monologue on puppets and strings.
What I find amazing is how good they are about keeping this stuff off the internet. In an age where everyone has phones, it's amazing that bootlegs of this Comic Con exclusive stuff so rarely make it out. I wonder why that is.