I've not seen this technique before, but apparently it works because of the pressure hits the wine, that hits the air and the air pushes the cork out. Rather neat I think, and not likely to cause damage.
Just to note: people have done tests on corks vs alternative stoppers and broadly speaking, for young drinking wines screwcaps are just as good as corks, don't need a corkscrew and don't have the problem of cork taint that natural corks can get. The writer Jancis Robinson has a comprehensive article about the ups and downs, if anyone's interested.