If you want to get good film footage of long fin eels then I suggest the wharfs at Lake Rotoiti in the south Island. The eels there are tame and even swim in the open during the day, water clarity is normally good and the eels would hand feed. Eels are protected in National parks so it is not a good spot to try and catch them. Might need a permit from DOC if you want to film in a National park.
I have heard a few stories of eels biting, rubbing against people ect…. Can be kind of scary in the dark. I would not beleive the story about the leg for a second. They might chew on it a bit but I would not beleive for a second they would do enough damage to require removal. I have had eels bite me once or twice while hand feeding them, they do not have real teeth and for the most part simply tear the skin.
I have caught a handful of long fin eels over the years and seen a few while trout fishing, but can not think of a place which would guarantee a good catch rate. Short fin eels are much more common and are easy to catch in most water courses.