If you refer to this video [1] the fact that the plane approaches "at an angle" is called "crabbing" and the "reorientation" at the very end is called "de-crabbing" [2], this looks very dramatic from the point of view of external onlookers, but it is actually more comfortable for passengers because it doesn't involve uncoordinated flying (in other words the plane stays "flat" instead of banking towards the incoming wind) and for this reason it is the preferred technique for airliners (as opposed to the other crosswind landing technique, which is called side slipping and involves lowering a wing into the wind). You can see a comparison of the two techniques here [3] (look at "Figure 1" and you will easily see the difference).
You are correct that ground effect is quite visible in that clip.
[2] actually in the clip this happens twice, crab, de-crab, then crab again then de-crab once more on touchdown. The Kai Tak checkerboard approach, even without crosswind, was an incredibly difficult approach and in this case the pilot had to perform a couple of corrections.
That video is the difference between "I bet I could land an airplane in an emergency, if someone talked me through it" and "apparently pilots actually learn something in pilot school".
[1] https://www.youtube.com/watch?v=OtnL4KYVtDE
[2] actually in the clip this happens twice, crab, de-crab, then crab again then de-crab once more on touchdown. The Kai Tak checkerboard approach, even without crosswind, was an incredibly difficult approach and in this case the pilot had to perform a couple of corrections.
[3] http://www.flaps2approach.com/journal/2014/6/17/crosswind-la...