Locking a plane to the view frustum. Use Ctrl+Alt+i to view a 3rd-party perspective.
The yellow lines mark the corners of the frustum.
Paired with aframe-video-billboard, we can build an Augmented Reality experience.
It even works in head mounted displays (eg; Google Cardboard)!
Note: The video's aspect ratio will be preserved by aframe-video-billboard, ensuring it never becomes distorted by center cropping the video.