You don’t get a look inside Apple’s factories in China all that often. Apple is notoriously secretive about their processes and products. That’s why the video below is so fascinating, as it offers one of the most extensive looks at an iPhone assembly line that I’ve ever seen.

Chinese blog Ynet reports that over 70% of Apple’s iPhones are now made in Foxconn’s Zhengzhou plant, where this video was shot. The video, courtesy of iFeng by way of M.I.C Gadget, shows a Chinese reporter from iFeng and Foxconn CEO Terry Gou taking a tour of the iPhone production line.

Gou first takes the reporter on a helicopter ride in order to show off the scope of the factory’s size. The video also mentions a few interesting details about the factory, namely that it covers the largest area, around 5.6 square kilometers, of any in Zhengzhou and it has the largest living area for its 115k workers.

Gou says that the area around the factory, which he refers to as a wasteland, is being reserved for further expansion of the plant.

The area of the factory that Gou shows off is dedicated to the production of the iPhone 4S and its display. The reporter shows off the iPhone 4S frame and Gou says that ‘his’ factory is better than any of the production in Japan, Germany, the U.S. and elsewhere. They then move on to the motherboards, where Gou says that one section of the parts runs some 148 meters. The motherboard area produces 10,000 units a day.

Gou and the reporter then step through a cleaning chamber and into a clean-room where the cameras are assembled.

The last video look at an Apple assembly line I can recall was shot by Marketplace reporter Mike Schmitz and that was of the iPad. It didn’t have nearly as many shots of the actual assembly, testing and parts involved in the making of an iDevice.

The site cites Mr Li Jiaxiang, the Administrator of the Civil Aviation Authority of China as stating that 70% of the production of the iPhone will go through the Zhengzhou plant this year, producing some 200 tons of international cargo every day.

In addition, there is a video of Foxconn workers being interviewed, but it’s not clear whether they’re working on Apple products or not. The workers are asked about working conditions and respond positively. You can see that here.

We’re working on getting a translation of the video above to see if there are any interesting tidbits. If you’re a Chinese speaking reader, feel free to chime in below!

 Thanks to Josh Ong for translation efforts