i didnt hear a hp sidechain there, it was a breakdown and the bass and drums went away basically, so im not sure what you mean in the song that does a hp sidechain, but the idea itself is shit easy, you know how you (i guess) normally sidechain to duck volume by triggering a compressor or just the channel strip volume, quite commonly used to get that pumping or sucking effect?
well, heres the difference, instead of sidechaining a volume to be pulled back, you sidechain a hp filter cutoff to be maxxed out. it seems people quite often have a rigid idea of sidechaining, and dont consider sidechaining as something that can be used to trigger anything other than volume or threshold.
i think sidechaining the decay on a reverb with the kick and then lowpass that every time the snare hits, and in the snare, make the 250 hz on the eq max out really quick when it hits. also link the snare to a hp dip on the pad. its fun.
but thats fruityloops for you, the peak controller can pretty much link everything to everything, its just fruity can get unstable if you have more than two or three peak controllers and then if you have a formula controller on top of that you should remember to save very often so as not to lose your work
There's no highpass filter. They just stopped to take a few beers while the breakdown was happening. If I remind correctly (i closed the video), that was just a big kick, with lots of reverbs, and also some hits from other instruments. Also called "impact".