Hate to say it, but I think these are faked. They always cut away a few seconds before he cums. I think they put some kind of tube on the side of the cock that can't be seen, then have her stroke it gently. Some of the spasms don't seem to be timed right, and the cum thickness seems a bit off.

It's a known fact that they loop some scenes in porn, so when you see a guy shoot a large number of squirts, it's probably edited in.