It looks like a bit of friction the whole way, not a free flowing fast cable ride.
I've done a zip line at a camp ropes course, here is my then 14 yr old daughter enjoying a little more freedom than those seats allow. The run goes across a gully between trees, I'll estimate 350 ft long and about 50 ft up at the highest.
My son was 5 at the time. The camp is called Okizu near Oroville CA, and provides a camp experiance for kids with cancer, as well as separate weeks for their siblings (who give up a lot of attention) and weekends for families. Thomas was too young to attend alone, so we went with him. He almost didn't make it to his second birthday.
They have lots of climbing and post and cable walks, even an elevated 'freeride' course for wheelchairs.
Okizu Foundation: Supporting Families with Childhood Cancer
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75 911S Targa - Mine from 2001 until sold to Germany buyer 10/2016
<ALL DIY> Brakes/Wheels '01, Body/paint/restoration 7/04, Suspension 3/07
Engine rebuild - done 7/08 - added 28 tube cooler and SSIs - running strong. Ducktail painted.
2021 MachE, 2012 Outback, 2019 Crosstrek, 2018 Impreza wagon