Amazon posted the 50-second video overnight, featuring various people looking at downward off-camera and saying things like "that is awesome", "it's very real-life," and "I don't know how you guys do it."
Check it out below.
Amazon has not released any further statements or details, but the general assumption is that the company will use the event to launch a 3D smartphone, as we previously reported back in April.
The video shows some users moving side-to-side while using the device, hinting that Amazon could be utilizing advanced eye-tracking technology that creates glasses-free 3D images via four cameras.
Reuters reported those same sensors will allow for tilt gestures, meaning users could navigate between apps and menus by moving the phone in different directions.
Customers, developers and journalists can request an invite to the Seattle event here, while the page asks questions like "Are you interested in developing apps utilizing a new type of sensor?" and "Describe an innovative way in which you have used gyroscopes, accelerometers, or other device sensors in your app development."
The company is expected to launch two different models of its phone, meaning a cheaper non-3D variant could be possible, or perhaps a smaller 'mini' version.
It's expected the device will run Android, given its Kindle Fire range of tablets already do so, while tech blog BGR reported the phone will have a 4.7-inch, 720p display.
That would mean the phone's screen would be smaller and lower resolution than 5.1-inch, 1080p Samsung Galaxy S5 and the 5-inch, 1080p HTC One.
Whatever the case, all will be revealed come 18 June.