The strength is impressive, however it does not have the "flexibility" that steel has. Carbon Fiber is also sensitive to heat and vibrations.
For a race car like Formula One it's great stuff but I wouldn't have the warm and fuzzy feeling using this for suspension parts or a driveshaft on a street car.
I would be really curious to see the same test performed after this driveshaft was on a car for 20k miles subjected to vibration, shock loading, heat from the exhaust (and exhaust leaks), freezing cold temperatures and chemicals like salt.... I wonder how that would affect strength.
I also wonder how temperature affects the material strength, looks like the performed this test at normal temperature like 70F - would the strength be lower at f.e. -10F ??
Funny: I had the same concerns about fiberglass leaf springs, now that I have one I really like it .... Still scares me that it could break....