Do DJI Goggles 2 support play back a video?

Yes. DJI Goggles 2 can be used to play back videos stored in the microSD card, or to cast DLNA videos played on the mobile device.
Supported video format when playing back a video stored in the microSD card: MP4 and MOV

DJI Avata FAQs

Source

https://www.dji.com/support/product/avata