So i have never done one of these before but ithought this was a cool shot so i figured id share it with NS on how i did it.
I am using FCP im sure other editing programscan do it just as easily but i am not familiar with them so i cant help you.
First step is filming the key is that the time-lapseand the slow-motion shot the camera needs to be in the EXACT same location. AKA you can not move the camera touch the tripod anything. Evenpushing the record button on the camera will shift it enough to notice a difference. So in this case i shot about 20-25 min in Keystone for the time-lapsethen hit pause and recorded JP doing his jump line without touching the camera.
Once the shots are imported drag them into yourFCP timeline and speed up your time-lapse by choosing 5000% or whatever youchoose. Then slow down your action shot to 80% or so. (These arethe % i used any will work. The next is to layer them in your timeline. The time-lapse needs to go on the lower video line and the action shot onthe top video line. Now select your action shot and go to the cropoption. The best way to do this is create a small box around your rider. Now in order for your box to move and follow your rider you will need tochange your cropped area. In order to do this start at one point with therider in the box set key frames for top, bottom, left and right. Thenmove the timeline until the rider is outside of the box you created then movethe box to fit him again and create 4 new key frames. Do this a few timesthroughout your clip and your box should follow the rider nicely. Whatthis does is everything outside the box you created will be the time-lapse andeverything inside (your rider) will be slow-motion.
Once this was done the shot is usable but inorder to create the pan in my shot i rendered and exported at full quality. Then i had one file to work with i changed the scale to 120%. Dragthe center point all the way to one side or the other set your key frame. Move in your timeline to the end of the clip set another key frame anddrag the center point the opposite side.