Me too, you can really build up quite some speed running through them and they look pretty impressive especially when there's a few stance shanges in there too.
The Whirlwind punch is a little like an overhead chopping punch but instead of coming straight down it comes down at about 45 degrees. It could be directed at the temple, kneck or collarbone. Once the first has struck it is immediatly followed by another from the opposite arm. This set of two strikes continues for 3, 5, or 7 times at quite a speed. It also looks like your doing a windmill impression with both arms. It looks as though it could be quite devasting if your opponent can't block/evade quik enough. I'll have to put it into practice the next time I spar.