For stillwater fishing I usually use 5X tippet material, which in the brand I am using tests out at 5 Lb. test breaking strength. For stream fishing I usually go with 6X tippet material, which tests out at 3.6 Lbs. breaking strength, both of which are beyond recommendation for most Seiryu rod makers. I am careful in how I handle my rods though, or at least I try to be. In most of the places I am fishing the terrain makes it very inconvenient or impossible to get down to the water's edge, and I also do not use a landing net for that and other equally valid reasons. The heavier than recommended tippets allows me to pull the fish up to hand to release the fish with a certain comfort level that the flopping fish will not be able to break my tippet and cause a loss of fly patterns. Most of my fishing involves one day to many-day hike in situations, where lost fly patterns are not readily replaceable. Most commonly available American tippet materials do not go below 7X, although few brands do go on down to 8X tippet material, which may still exceed the Seiryu rod maker's tippet recommendations in breaking strength by a good margin.
I have given the challenge of using tippets within the recommended weight range some consideration. Doing so would make catching even of average sized trout and bluegill a much more challenging angling undertaking. I believe long line technique places tip casting rods in the greatest danger of breakage when the rod must be laid back so that the line can be grasped by the angler to hand-line in a large fish, placing and concentrating the maximum force on the rod's tip section in that case. In running water this is not as big of a problem as it is for pond and lake fishermen, because the fish can be allowed to move either upstream or down, more or less parallel to the angler's position with the current's help or resistance as the case may be, allowing the rod about a 180 degree range of movement. But on stillwaters the fish will often move directly away from the angler or go to the bottom and sulk, where you have no lifting power left in the rod and the line will often still be well out of reach. Timber directly behind you limits how far the rod can be laid back, so you are pretty much stuck where ever you find yourself and the fish. The only solution for this problem that I have been able to come up with is to fish a line that is short enough that it will never be totally out of reach. At present I am walking a fine line between a line that's long enough to reach the fish and be stealthy but still short enough to allow the playing and landing of fish effectively, with out putting undue stress on the rod and concentrating that stress on the rod's tip section. However, I have not been able to arrive at a totally satisfactory solution so far.
I tend to agree with GregM in that the breakage in the lower rod sections at the joints of Den's Air Stage rod was probably due to some kind of undetected manufacturing defect inherent in the rod itself, more likely than do to too strong of a tippet Lb. test rating being used. The clean, abrupt breaks shown in the video are the type that result from post manufacture nicks and bruises and or manufacturing defects. Since this was a new rod, the possibility of the rod already having been damaged is relatively slight. The large, ragged, catastrophic appearing breaks shown in the video demonstrate good to excellent rod blank integrity, with no manufacturing defects present. And when sideways pressure is applied, the joint itself can and will provide all the fulcrum point needed to shear the rod blank into two pieces. Den, were your breaks relatively clean and closer to 90 degrees or of the diagonal and ragged type? Western fly rods utilize thread wraps to re-enforce the female ferrules to help prevent splitting of the rod blank material at the joint. I don't believe fixed line rods utilize that re-enforcing construction technique. Perhaps, they should.