I have seen that before (not that particular video, but videos of that species of anemone,
Stomphia coccinea). It's a coldwater species (ie., this is one specific species who has evolved to use this behaviour). It's "swimming" is a flight response to a threat from a predator. You have to admit, it's pretty effective.
Not sure of its range, it might be all the way up into BC. I think its range is for sure as far north as the Puget Sound though, so could well be up into BC waters.
PS. Forgot to mention. Cool video !!! Thanks for sharing the link.