The coup didn't happen instantaneously at a given time, so it seems reasonable to say the video was recorded during the coup. At the same time, it's not really clear what specific activities the vehicles were on route to.
She seems to be dancing by the Royal Lotus Roundabout near the Parliament and Presidential Palace [1].
The building in the background of the video appears to be a shrine located just past the road leading to the Presidential Palace. You can see the vehicles turn left just before the shrine, so they were probably up to no good...
Coup news takes time to reach the media. If this is not fake more likely this video is from the previous day afternoon, when they raided the parliament.
This stated communication blackouts lasted from 3 to 1115 am, with one journalist reporting a loss of service at 4am: https://www.bbc.com/news/world-asia-55893736.
The coup didn't happen instantaneously at a given time, so it seems reasonable to say the video was recorded during the coup. At the same time, it's not really clear what specific activities the vehicles were on route to.