Videos appearing up-side down/sideways can occur when users record videos from their devices and then uploaded to the Aurasma Studio.
Pretty much all devices have screens that auto-rotate, however this only rotates the user interface - the video itself is still recorded up-side down/sideways. The reason the video looks fine on your device and on your computer is that the video contains information that tells the software on your device & computer which way up the video was recorded. This info is lost when the video is uploaded to the Aurasma Studio.
A solid rule of thumb is to ensure you're recording your videos the right way up in the first place - typically with the home button on the right when held landscape, however there are a couple things you can do after the fact to get them the right way round after the fact:
1) place the video in your Aura as best you can.
2) click the 3D view button, then click inside the new popup window - drag the view around, but make sure you wait until the video has loaded before doing the next step.
3) hold down the A key and press the left (or right) arrow key button on the keyboard. Every arrow key press rotates the Overlay by 10 degrees, so 9 presses gets you the 90 degree rotation & 18 presses rotates it a full 180 degrees.
4) Hit save - when you return to the 2D view.
5) Save the Aura and view it on your device. The video should be the right way up!
Note when you save & close the 3D view window your video Overlay may appear squashed/flattened on the 2D work-space. Don't worry about the way your Overlay looks on this screen - it will appear the way it does in the 3D viewer when seen in the Aurasma App. If you pull it around in the 2D view it'll mess up the rotation you've applied to it in the 3D view.
Pro tip: In the 3D view, using the mouse scroll wheel when any command key is being held will change the increment number (default 10) so if you scroll it up to 90 you'll be rotating by 90 degrees with each arrow press, similarly if you want a more precise degree of control, mouse wheel down to lower the increment & rotate by single degrees (or less!) at a time.
Another option would be to use some video editing software to rotate the video before you upload it to the Aurasma Studio - obviously you need to get your hands on some software for this.