It sounds like the video is saying (link with a time stamp corresponds the following)
Grylls lived his childhood dream to climb Everest when he scaled earth's highest mountain in 1998, less than two years after his near-fatal Africa fall.
cambridge gives these explanations
a set of numbers, amounts, etc., used to measure or compare the level of something
the relation between the real size of something and its size on a map, model, or diagram
the size or level of something, especially when this is large
None is suitable in this case.
Does "scale" mean "achieve", "plan" or some other meaning here?