When changing the header video, with a upload.
The default video (brown chocolate), is visible for a fraction of a second.
What can i do?
It was solved by removing the default videos and photos via ftp. But after a theme update, it came back.
Hi there
Hope you are having a good day and thank you for your question 
In order to check your question i need to see your live website, please provide url and i will take a look
Regarding method itself, you should not upload video file like that, you have to change it from the options panel, otherwise it will be changed back always on every update