Around 5 kts the fin creates lift, the nose lifts and she (unlike my other boards, the Serenity justifies a "she"!) starts flying along. Below 5 kts she cuts through the water very smoothly and quietly, a serene experience! Unlike a "normal" board in light winds, the Serenity accelerates very quickly from rest; hard to describe the experience unless you try one. If you can feel a breath of wind, she will go!
For me, the speed is irrelevant, the Serenity is just a load of fun from 1 knot upwards and will keep me sane during our many non-planing days.
The movie will be completed at some point in the future. Right now we are in the middle of the north east monsoon in Thailand, which is not normally Serenity weather. Today I was out on my Carve 111 and a newly acquired 2007 model 6.0 Gator; lovely sail. But when the wind dropped at the end of the day I got some nice sunset sailing shots of a friend on a Serenity.
I like your fishing line idea...!