( Play it from 1:12 to start from the [B] part )
what is that D#m7(11) ? how does that leads to Gmaj7 ?
The V7 in GMaj is D7, and the tritone substitution for D7 is Ab7. The minor ii chord which leads to Ab7 is Ebm, the chord you're seeing here. Normally, we would see | Ebm7 | Ab7 | GMaj |, but here the V7 chord is omitted. So in terms of function, I recommend thinking of this as the first half of a tritone substitution which resolves straight to GMaj without first passing to the V7 chord.
In addition, something else that's happening here is parallel movement. The min7(11) chord starts on F#m7(11), then moves down a whole step to Em7(11), then moves down a half step to Ebm7(11). This sort of parallel movement is worth mentioning because it can appeal strongly to the ear even when it doesn't follow any traditional harmonic function. When seeking to understand why this sounds good, we'll want that parallel movement to be part of the explanation, too.