//TEXT VERSION//
#1 For this you’ll need four videotracks. Drop your picture of choice into the first videotrack.
Right click on it – Video Event Pan/Crop – 16:9. Place it somewhere on the left size and maybe resize it a little bit
#2 Go to Video Fx – Cookie Cutter – “Square, Center, White Border” and add it to the picture. Change “Border” to 0, “Repeat X” to 3 and the size to 0.125. Change it so it’s on the left side.
#3 Re-do this with the next three pictures (same preferences) but move a little bit to the right side with every picture (I left a really small black streak between the pictures)
#4 Resize the clips so they form a pyramid.
#5 Go to Transitions – Linear Wipe – “Top-Down, Soft Edge” and at it to the beginning and ending of every clip
source