That is really cool! I haven't tried hot plates because I didn't really have faith that solder would actually pull the component down and align it. I think this video might have improved that faith :-)
To counter the sibbling comment: I've assembled many dozens of boards on a hotplate with no complaints. Watching them reflow with a stereo microscope (AmScope SM4) over the hot plate is fun. I've never worried about temperature profiles; I've just started it from cold on the maximum setting and turned it off when all the solder has melted.
Using a hotplate is like driving with one eye closed. Sure you’ll get there, but your accuracy will suffer!
Though I’ve had many a SOICs magically realign on the hot plate — they were pretty forgiving — it’s not worth it to run without proper temperature profiling, even if it’s from a hacked toaster oven :)
