Dogging, stumping, graveling, hogging, tickling -- the practice goes by many names.
Here in Oklahoma, they call it noodling.
Wikipedia has a pretty good description.
According to Wikipedia, the origin of the term noodling, is the word noodle, which is slang for a foolish person.
Seems about right to me.
P.S. - I don't think these Thai fellas caught their catfish with their bare hands, do you?