A quick scan of the video (little point in learning more about the current command syntax when it's about to be rewritten) does not show how this was done. (The narrator handwaves the comnbining process @ 2m50).
You can make something that looks like that in vanilla by using a piston to force a block onto an armor stand, given that the up & down movement is done with command blocks however the video maker may just have gone that route.
Rollback Post to RevisionRollBack
WARNING: I have an extemely "grindy" playstyle; YMMV — if this doesn't seem fun to you, mine what you can from it & bin the rest.