It's just a gut feeling but I'd trust a feedback based backlash elimination mechanism more than rope based, especially in the long run and/or with a large deployed base.
Anyway good engineering requires extensive testing over many hours of movements.
He actually discussed this in an earlier video for his initial tests on the capstan drive. He ended up testing the rope he used for around 358 hours (two weeks) on continuous use in the drive itself with very low backlash