Its not the greatest quality video, and like most videos they never point the camera were l want to look:-(
Still as more become available, they gradually fill the blanks that l have from the data that Isida project sent me.
The circular impressions visible on the corbels are interesting, (and present in both chambers) l unfortunately do not have the full picture of their locations, but its possible that they held beams. Originally the face of the corbels would have rough stock left on the block, in which a hole was made to hold the end of the beam; the opposing corbel would be done likewise, and when the corbels were pushed into place, the beam also acts as a spacer, and scaffold to hold planks that allow the workers to dress the face and leaving these tell tale depressions.
The other square holes that are visible, the data is unfortunately even less.
Its a pity that the best data from the structure has to come from tourist videos:-(