Perhaps a basic understanding of combustion is in order:
On Earth, our atmosphere (~78% N, ~21% O) provides the oxygen. In Space, a solid or liquid propellent rocket engine provides an oxidizer in the form of liquid Oxygen, or some other chemical compound that contains oxygen. Thus, the oxidizer provides the oxygen in lieu of the atmosphere
Conspiracy theories can be fun, but only when they are not objectively demonstrably false. You really should read up on this before you post anything else, lest you come across as willfully ignorant.
The myth busters video has been debunked; same with the second one, where he didn't keep the meter in view the whole time. The problem with your own hypotheses is that matter expelled in a vacuum would be dispersed at an amazing rate of speed, and without walls, in boundless space, there would be nothing for the rockets to propel against,
except, if you believe NASA, maybe this giant astronaut in space?
Maybe he could throw the rocket or allow it to push off his head?
https://www.youtube.com/watch?v=0pVm7p4nkwo
NASA is too funny. Note that the astronauts have no suits on to traverse the Van Allen Belt.