Your search has turned up a lot of wrong information. I would stop using info from that site if I were you.
AS HT says...that's the nozzle and it should flick back and forward at a really high speed when you shoot the AEG.
How are you winding your mags? Are you winding it properly...by properly its not the wrong info on the net where you just give it a few cranks. You give it like 100 cranks.
Here's me canking an AK Mag to max whind and then burning off ~300 rounds with it.
See how long it takes to wind...over 1 minute.
Also, for the silicone oil this is sadly a propagation of a bad translation be in ignorant individual. It is the blind leading the blind. Back inthe early 1990's Airsoft guns ran on air tanks and the gun had an internal piston. Instead of tearing the gun apart. People would put a few drops of oil into the "compressed" air tanks. Then when the guns went to Refrigerant as a power source, Silicone oil was needed because refrigerants would cause latex seals to leak.
So when Green Gas switched from Refrigerants to Propane. The "idiots" carried the oil into modern day green gas not fully knowing why you truly needed the oil.
And when they tossed it into AEG boxes...they Assumed that was what you used to clean the barrel...add in the internet and more misinformed people...the improper maintenance procedure is set in stone and preached as the gospel.
As for the bbs falling out. That is "normal". These are the bbs that are above the detente of the magazine and below the nozzle in the AEG. This is the hop-up feed tube. If you drop a mag with bbs in this no mans land...they will just fall out.
Who made your AEG...that looks like a MPEG/LPEG feed tube.