I did not see the vid but if the sliders have to be removed for reefing...well, l had the same problem and l could not comprehend that on my yacht. In my experience, by the time l got to the third reef the sail was unmanageable, wind increasing, besides, looking like an Easter ham with the ties around it.
Imo it is not safe, extremely difficult to achieve, overly laborious and in circumstances it could become outright dangerous to equipment and, or crew.
I am not critical of other sailors, far from it.
I had the same problem and had to solve it, which l did, creating enough space between boom and tack-cringle position by moving the tack position just a bit higher, 're-positioning the horn and making a new lockable mast gate further up the mast track - before only having a slit in the track but no gate low down on the track - at the appropriate height for making it possible to employ all three reefs without the removal of any sliders.
I found, having a fully battened main makes the reefing easier by far.
The gale force setting on Rhapsody is easy. Furl the jib, bend the cutter sail, 6,2 sqm, and the third reef, 4,9sqm and carry on.
If this would prove to be still too much, l would bend the 2,2sqm storm sail and the trisail which would cause a problem as the tub does not have a second mast track.

Luckily, l never ever been even close to that possibility.
