Filmed and edited by Muir and his partner Rita Phillips, the video is a mini-movie of love going wrong and coming right again. Muir's sister Mitch plays Smith's love interest.
It is one of a dozen NLC videos on YouTube and each one tells a story.
Dylan Thorby-Reid was recruited for Love Not War and says the experience gave him a "massive confidence boost."
"I had to run towards the camera and get shot.
"I really hurt my back when I landed but it was such a good experience."
Muir says he enjoys giving young people opportunities to shine and seeing their confidence grow.
"Sometimes I want to deliver messages with my songs and others are about love for whanau and friends," he says.
NLC is a whanau affair. Muir's adult daughter Shaye is a band member as well as a solo performer.
Muir and Phillips have a baby daughter Sharlisa, who appears in the Say Goodbye video.
The band were finalists in the 2017 Waiata Maori Music Awards and were nominated for the Best Maori Urban Roots/Reggae Album award for their second album Love not War.
"It will be nice if we get nominated again this year," says Muir.
"The ceremony in Hastings last year was an awesome event."
Say Goodbye is to be included on NLC's third album which Muir says he has not yet named.