Hi I saw this video - https://youtu.be/4ezKmawMEUs From your official YouTube page, in minute 2:40 he says that Sony mirror less cameras bring 2 batteries, so I want to know if that is true and if I buy my alpha 7 will bring 2 batteries?
The battery for the A7 series was originally developed for the original NEX APS-C mirrorless cameras. The 'Full Frame' A7 series cameras draw a lot more current, so that battery didn't last as long. To compensate for that (somewhat), Sony includes 2 batteries with the A7R II and A7S II.
The new A9 uses a new battery that is more than twice as powerful as the battery that the other E-Mount bodies use, and is even more powerful than the battery most A-Mount cameras use.
¹ The Lens is the Thing ² 'Full Frame' is the new 'Medium Format' ³ "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.