slow mo and speed up are fine for syncing, but your replay had no natural speed areas, or close to natural speed to sync with.
your vid was great for the length of the replay, and creating sync is still cool and fun to watch, but for longer length vids, use that kind of sync for choice pieces.
try using the speed up/slow mo very slightly to sync the body of the vid to the general beat, then choice moments of amazing.
Check out some parkour and breakdancing vids for syncing fluid movements.
hip hop, popping and locking, robot vids for syncing to specific beats.
faking normal speed for locking type sync would actually be pretty cool, with fast interganging slow mo and speed up, just gotta work on the camera work so the changes arent too noticable.