This is not a slip. In S Florida with all of the canal front docks, it is traditional to cross tie in the middle of the canal during Hurricanes. This moves your boat away from the dock, while blocking the canal from other boats. You can see my dock location in the below image.
This normally works well.
We had 2 of these very heavy snubbers break - one during Irma, the other during Maria. These were for 1" lines. As I recall, they were pretty costly, and they didn't do their job. They bothe snapped clean, right in the middle.
I had two on my bow lines from 1998 to 2016 (when I moved). 1/2" dock lines, the things were probably big enough for 3/4" line. A year before I left the starboard one broke in the middle. This was in a very protected marina. Not something I would "depend" on.
I have always been taught that dock lines are for several reasons. Bow and stern lines should be just long enough to keep the boat from banging into any pilings or docks. For example, in a slip, the starboard bow and stern lines hold the boat just off the dock or pilings or neighboring boat. The port lines do the same for the starboard. This allows the boat to move within the confines of the slip without banging into stuff. They have slack. Spring lines, on the other hand, hold the boat steady front to back, while allowing a spring in the shock of hard forces. Bow lines, stern lines are slack, spring lines are tight. The length of your spring line and its stretch should allow for the tide to rise and fall without significant movement of the boat. It is a lot different to tie to a pier in NE with 8' tides than to tie to a seawall in South FL with their 3' tides.
If your cool video was at the storm's peak winds, then your boat was perfectly pointed into the wind's direction or Minimum wind force on the lines.
Luckily there was a empty canal near our marina, as all marinas were under mandatory evacuation.
At the height of the surge, the water was over a foot above the pink paver deck in the video, so only 4 to 5 feet of surge. I don't have video of it, but when the storm eye passed over, and the wind shifted to the south, the neighbor across the canal said he saw our boats leaning to port almost 45°. That was with just mast and boom, no canvas at all. Luckily there were no trees close to the edge, or we may have caught the rig, and had a real issue. Some of the members of my sailing club removed their booms as well, and stowed them below. I don't know how much that would help.If your cool video was at the storm's peak winds, then your boat was perfectly pointed into the wind's direction or Minimum wind force on the lines.
Hopefully there was no wave of water [storms surge] that entered your canal.
BTW, as a side note, I used your technique to tie off for Hurricane Nate. I allowed for 10' of storm surge. Not a scratch.
Good Job!
Jim...
Sounds normal, but then the openness of the canal is providing a direct low resistance to winds.
Boats, Masts and booms are designed to have low wind/water resistance, as your boat points into the wind, I would suspect the wind on the boat's hull profile is the key to wind force.