From listening to it, in this case it's definitely quite heavy side chain compression of the bass off the kick channel... You can hear the bass synth pumping and the sound of the compression release after each kick.
Admittedly as btownpro said, it didn't sound amazing in the lows to me but that isn't helped by the YouTube compression of audio / whatever it was uploaded as!
I'd say first and foremost the best way to get a kick and bass to work together is to write and produce it that way. Use instruments/sounds that work together (including phase relationships) and play them/sequence them in a way that works! There's nothing worse than getting a mix to do with 3 layered kicks and 3 basslines and the comment "can you make it sound like this massive 808 track by...". There's a reason it doesn't sound like that and most of it isn't the mix
For me one of the starting points for getting a clean kick, bass, snare and lead vocal is pan. It's also the most natural. I wrote an article about this on my blog:
Dights Blog - The Most Valuable Real Estate In A Mix
Then I feel the next most important thing for kick and bass is level balance and subtractive EQ. EQ cuts in the right place. Cut for clarity and boost for vibe. Balancing the low end is just like anywhere else in the frequency spectrum, you only have a finite amount of space... However low end energy takes up far more space than high end!
It's not only about getting the level and EQ right in the bass/kick relationship, it's about doing this for everything around the kick and bass. Get rid of everything else in that frequency range that is getting in the way of the kick/bass energy. Additionally if you get a nice low end EQ balance through cuts you'll have enhanced the clarity and removed a lot of energy, this will probably allow you to turn up the bass in level.
Beyond that there are then plenty of other methods of enhancing this, including the use of compressors, side chain compression, m/s techniques, sub-group bussing, etc.
I hope that helps.
