He's not explaining it very well.
He's talking first about a triplet shuffle rhythm, which is pretty standard in blues (and which you hear in his backing track). He's saying that's a bit "hokey" (in his opinion), and by "smooth it out a little bit", he mains "straighten the 8ths" a little (in solo phrases over the track).
That's actually
more like swing, because swing is never that "hokey" exact triplet feel. It's a variation between straight and triplet feel.
IOW, he's saying you should swing your phrases rather than play solidly on the beats (or the triplets) all the time - and he's right: you have to
feel the rhythm, not treat it mechanically.
(However, I don't think the way he plays sounds very good. He is consciously straightening the 8ths a little, but it sounds clunky to me. It would sound a whole lot better if he played right with the triplet feel, but varied his accents more.)
In fact, it's quite common in blues (more so than in jazz) to follow that hard triplet rhythm quite closely - because it
grooves when done right (with the right kind of accents). "Swing" (in jazz or blues) is looser and more variable.
It might help to see it visually:
4/4 time (straight 8ths): |1 & 2 & 3 & 4 & |1...
8th triplets (12/8): |1 & a 2 & a 3 & a 4 & a |1...
BLUES SHUFFLE: |x x x x x x x x |x....
JAZZ SWING: |X <-> X <-> X <-> X <-> |
The "<->" shows the variable range of swing. I.e., it's like the straight 8ths are delayed slightly, maybe as far a triplet feel, but could be anywhere in between. In particular, the faster the tempo gets, the more those triplet 8ths will smooth or straighten.
It's a more loose, lazy kind of feel, with a lightness of touch. It requires a fair amount of experience listening to (and playing) jazz to get it right. It's common for classically trained players (despite technical brilliance) to find it extremely difficult (if not impossible).
Here's some classic blues shuffle, with very little swing, if any:
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forum.emusictheory.com]
You can hear the triplets strongly marked in the piano and drums, and the guitar follows that rhythm quite tightly. Is that "hokey"? (If it is, I like hokey!).
Here's a looser blues feel:
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- but still a firm underlying triplet feel. The 8ths never really get straightened at all.
However, I would also say this "swings" - very much! - as I define it anyway. I think it's because those in-between 8ths are not heavily marked (as in the shuffle above), only implied.
This track is also an example of what he describes (around 0:50) as "hanging back", "behind the beat". It's a very subtle thing, but you should hear that the snare tends to hit very slightly late from where you might expect it (mechanically) - it's what gives the track its tremendous feel. This is
extremely difficult to reproduce consciously! It's pure attitude, pure feel. You can develop it, but it takes time, and a real love for the music.
The "swing" thing is a lot easier to comprehend!
Here's a faster Muddy Waters tune:
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This definitely swings. The 8ths are
almost straight, but not quite.
Here's some classic jazz swing
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The in-between 8ths are definitely delayed - swung, not straight. He occasionally squeezes three triplets into a beat, but mostly it's two 8ths per beat, the first a
little longer than the second. If the tempo were slower, the 8ths would be more different: the first more noticeably longer than the 2nd - IOW, the 8ths between the beats more delayed.
How about this:
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www.youtube.com]
In this one, the piano is playing straight 8ths (very nearly), while the drums and other instruments are swinging - delaying the in-between 8ths more than the piano is. This creates a
very loose feel. The beat is solid, but in between the beats nobody is really synchronising - they all seem to have a different idea of how "swingy" it ought to be. Sounds great though, right?
IMO, the best way to think of this feel is as "lazy". Get into the groove, feel the beats, but in between the beats you can be as loose as you like.