Time until hypoxia is greater in a gradual decompression compared to an explosive decompression. Gradual decompression events are insidious in nature, they can easily go undetected.
So the oxygen bottle ruptured, took out the transponder and the cabin altitude warning system but left most other systems intact. It ruptured a hole in fuselage just the precise size needed to let air leak out at such a small rate it would not be detected. Even the tiniest of holes is still going to have air leak out of the cabin at a rate of about 1000ft per minute (and I'm being very generous there, in reality it should be much more). At a cabin altitude of 8,000 to 30,000ft (where useful consciousness is about 1 minute) will only take 20 minutes. But we know that someone made a deliberate course change at least 1 hour after the initial deviation, when the aircraft was heading WNW towards the Andaman Islands on it's last radar verified track to turn it to the South, around the top of Sumatra towards the Southern Indian Ocean.
So even if this "magic oxygen bottle" exists it still doesn't match with known evidence. QF30's ruptured oxygen bottle caused an almost instantaneous loss of all cabin pressure when it breached the fuselage.
The incident with the Kalitta Learjet in the previous video lasted a grand total of a few minutes, from the pilot descending from FL320 to a more breathable FL110. A few minutes, the time of useful consciousness at FL320 is about 1-2 minutes, so even though he was slurring his words (hypoxia effect) he had just a minute or two to get the aircraft down to more breathable air before he lost the motor skill capacity to make control inputs. MH370 was at FL350, wher time of useful consciousness is about 30 seconds. Yet the decompression story requires us to believe that a pilot stayed conscious in that environment for almost an hour with no supplemental oxygen then made a control input to turn the aircraft to the south? Simply not believable.