I have a video of Wudang Mt. snake style kung fu. I think that and the Emei style are what you would call an "Internal" style. The video is 90 minutes long and full of applications. Snake isn't a major style but you can still practice it. There is a nearly dead style called cobra style I was reading about on a Shaolin website. Very Brutal, a Cobra apparently just sort of bites and holds on till you croak, so you can imagine it's probably not a very nice style to spar against. If the Hung Gar guy is saying that Snake is not a complex enough animal for a practitioner to mimic in a form, realize that the level of interpretation in kung fu is often rather abstract in regards to the animal forms. The Dragon being the most obvious example