They call it 'Dawg' music. ( Jerry Garcia came up with that name when he met David Grisman to record an album. )
Not really bluegrass, more a mixture of Bluegrass with Django Reinhart, Stephane Grappelli Jazz.
Not sure what category it falls into.
Have seen this group over the years live and they always deliver.
A long song, but it really takes off after the 2:00 minute mark.
Some fine picking and Flute.