Not bad, but missing some details. Sure, magnetic exploders were junk in those days, but the real details of the impact det was not explained. When they hit at 90 degrees straight on angle, the firing pin, which was sideways, experiences great friction and did not put enough force on the primer. Off angle hits would usually work.
https://www.historynet.com/us-torpedo-troubles-during-world-war-ii.htm
The internal failures of the contact mechanism can best be understood through the forces at work in a live torpedo. When a 3,000-pound torpedo traveling at 46 knots struck the hull of a ship, incredible forces were unleashed. The initial force of deceleration equaled approximately 500 times the force of gravity. Transferred to the firing pin, this force appeared as friction between the pin and the guides along which it traveled for accuracy. These stud guides were exposed to nearly 190 pounds of pressure from the contact and resulting deceleration. The firing spring was unable to overcome this tremendous friction and pressure with enough force to drive the firing pin successfully into the primer caps. When a torpedo struck a glancing, angled blow, the force of impact was lessened enough to allow the spring to push the pin into the caps, causing detonation.
The solution turned out to be relatively simple. The Pearl Harbor workshops designed and mass-produced modified firing pins from the propeller blades of Japanese aircraft downed in the December 7, 1941, attack. The new pins were made as light as possible in order to reduce the friction on the stud guides. Testing this handiwork, Lockwood ordered the submarine
Halibut, armed with modified exploders, to repeat the Kahoolawe tests. Each torpedo was again set to run as close to 90-degrees as possible to fully test the new pins. Six out of seven torpedoes exploded. Although one still failed, it was a significant improvement from a 70 percent failure rate.
During the 1930s, the Bureau of Ordnance had conducted similar tests designed to ensure a reliable contact mechanism in time of war. The Newport Torpedo Station flung torpedoes against steel plates over sand and discovered then that the firing pins failed to strike the caps with sufficient force. Their solution was to increase the strength of the firing spring. The tighter spring seemed to solve the problem, but it did so at the speed of 1930s torpedoes. Torpedo speeds had increased to 46 knots by World War II, and this increase created greater impact forces. The increased speed essentially negated the strengthened spring. If
Tinosa‘s torpedoes had been set for slower speeds or obtuse angles,
Tonan Maru No. 3 would not have escaped. It took almost two years of wartime trials and tribulations, but American submariners were finally equipped with reliable and effective torpedoes.
NOT MENTIONED IN THE VIDEO is that 2 US subs were sank in WW2 by their own circling torpedoes. I think if they would have dove deep after firing, they would have survived. Note that all modern US units have an extra gyro whose only job is to prevent firing in this event.
ALSO, they did not mention the cool Japanese Long Lance, the best one of WW2. Bigger, faster, longer range, and bigger warhead. And used PURE oxygen for oxidizer, a real problem as it took 2 days to purge all the oil out of the plumbing before fueling. As anyone with a cutting torch knows, the smallest amount of oil in your O2 lines will create a BOOM.
https://nationalinterest.org/feature/japans-super-torpedo-was-the-hypersonic-missile-wwii-15541
Our modern torps use a swashplate engine. Weird. Pistons thru a linkage make a plate wobble, which translates to rotation. Very powerful maybe 500-900 HP. Uses OTTO fuel which is like liquid TNT, has all you need to burn, the gas is distributed to each cylinder, and a rotary valve routes the exhaust thru a hollow propeller drive shaft exhaust. When they scaled up the first prototype, it exploded and almost killed people. Nice story: A test of the MK48 was being viewed by an overhead chopper. The rotor blades created ripples on the water, which the torp seeker responded to. It headed up, flew out of the water, and almost downed the chopper! True story, I worked at the Westinghouse plant, but on other stuff.
Here is my fave, the ASROC. Rocket powered, nuke warhead. LET'S ROCK!