TIMELINE
In terms of when this short takes place, at the beginning of the video we get a short glimpse of Mei right before she went into cryogensis. At age 31 she entered into the chamber where she stayed frozen for nine years. Her 31 year age is her biological age and does not take into account her time frozen, which was confirmed by Overwatch Lead Writer Michael Chu. Therefore, if she hadn’t been frozen, she would be 40 in the current Overwatch timeline.
When Mei entered cyrostatis, Overwatch had not yet been disbanded. During her nine years frozen, the group had been disbanded due to “overwhelming negative public sentiment and allegations of corruption and abuses of power.” This doesn’t quite explain why no one would go back to check up on Ecopoint: Antarctica after Overwatch was disbanded, however in the screenshot shown above when Snowball shows Mei all the headlines explaining the end of Overwatch, there is one news story that states the base was lost in the polar storm, meaning no one was able to even find Mei and her team after it hit.
The conlusion of the video has Mei recieve a transmission from Winston, which many will recognize as the opening video for the game itself as well as the premise to one of the first Overwatch animated shorts “Recall”.
After Mei leaves the Ecopoint, in her journals she states she visits Winston and then goes to the Yukon, Asia, Los Angeles, and then back to Asia in the Himalayas.
