It doesn't really matter if doesn't sound like a 100+ mph
serve or looks like one, etc. The radar read 100+ and I
seriously doubt drakulie doctored the video.
It could be the distance or angle from the baseline that's making the
serve look slow. Usually serves look slower on camera vs.
in real life. Sort of like how people look about 5-10 lbs
bigger (or fatter) on camera vs. in real life.