I've never seen another person (even the instructors) at my range using video. I've had a couple people ask what I was doing and seem surprised at the ability of the iPhone 240fps mode to capture swing positions so clearly. 

I can count on one hand the number of times I've seen someone Taping their swing at the range.  But I do think it is becoming more common based on the number of instructors offering online instruction like evolvr.

8 hours ago, iacas said:

I think the fact that more and more phones have 240 FPS video makes it that much easier.

When I worked at a golf course in high school, late 90's, our pro had this big 'ol cart with a video camera system.  Whenever he would want to use it I would have to wheel the whole system out to the driving  range.  The video was pretty terrible quality compared to today.  When the lesson was over I rolled it back in and made sure it was plugged in to charge.  So yeah, taping your swing with a quality high fps camera on your phone is a little easier.