View Reference Images In All 3d Views I recently watched a video on YouTube that used two images simultaneously for front and side views. The images don't disappear when the speaker moves around the 3d-viewport. It's a little difficult for me to explain it in words, please watch the video to look at the image orientation.

I would love to know how that kind of image reference would be possible, because when I load any images they're only visible in one view and disappear when I switch the view.

Please let me know if any more information is required.
I guess, that is not the case, he is using one image for the front view and one for the side view and as he is switching between views using a short key so its look like he has background image for every view 

Background image is disappeared in many views, take a look below: