The way I see the setup in the vid: One main beefy line, static, tied way high on the left, a redirect near ground level on the right, the mini seen at the end controls the tension.
The smaller line holds back the log, controlled by a groundy with a porty or cabestan at the stump.
The moving block holds the log and rides down the main line.
A span rigging setup would have two equal ropes, as each have to do the same work, each on a block high on the right and high on the left (or one on the spar and one far away), each rope controlled by a cabestan of some sort. By adjusting the tension of both ropes, even in taking slack if needed, the log can go nearly anywhere between the two blocks, any point in the air included. Handy to pass over a tall something on the way. The controled speed line allows only a travel under the main rope, aka a triangular area. The setup can vary of course and may be an hybrid of the two.