osama flushes from behind the engine, which is actually the correct procedure, This way the water from the back and also the front of the thermostat is flushed out - In simple words, he backflushes from the bypass coolant lines, Its pretty much standard way of working.
The removal of pipes from radiator etc is not required unless you are installing some flushing jig/tee.
The silicates deposits are removed abt 80% with a mild flush - they will eventually make their way out into the expansion tank (thats why I recommended to keep an eye on it and clean it when it gets dirty). To remove 100% deposits a very strong flush is required which can cause leaks if your system is unknown (you have a scrapyard engine which you never opened up - its risky that way)
