After submitting my application, I received a video interview about 3 weeks later. The first video interview is the same as the Delta Air Lines standard flight attendant interview (same questions as those the most recent interviewees mentioned). After another 2-3 weeks or so, I was offered to do the second part of the interview process. This was the language test, also done via webcam.
I know this seems extremely obvious, but I still want to clarify that the Mandarin language test is done completely in Mainland Chinese. In other words, all Chinese text is in SIMPLIFIED Chinese and all spoken Chinese is in the BEIJING accent ONLY. (Taiwanese applicants be aware.)
For the first question, you are asked to read a script (Simplified Chinese characters) aloud. It is a script for an inflight announcement.
For the second question, a video is played. A man asks you a question (in a VERY heavy Beijing accent by the way) once, and then your answer is recorded through webcam.