It's an urban legend
. There explanation is copied in below:
Origins: One of the hazards a kayaker might least expect when plying ocean waters is for a killer whale to breach the surface and land on him, but that's what is depicted as happening to one of a group of three kayakers on the video clip displayed above. (The capsized kayaker resurfaces at the end of the clip and, apparently unharmed, rights his craft.)
However, this clip, which circulates under the French joke name of "Regis fait du kayak," isn't the real thing: It's part of a Korean-language version of a commercial for Powerade energy drink (a product of the Coca-Cola Company). Powerade is noted for producing commercials using a variety of tricky visual effects to depict athletes accomplishing seemingly impossible feats of strength and skill (to the accompaniment of breathless narration by on-the-spot announcers), and this kayak commercial is yet another example of that genre.
In this case, the commercial's producers took some footage available in the documentary Lolita: Slave to Entertainment (viewable in the film's trailer and added the kayaks through digital manipulation.