suppose a video was created using tails then uploaded to a site, does the metadata change?
theoretically it should, since the file is now on a different computer and thus the host should give the file new owner id and timestamp, right?
now lets build on that and say a user downloaded the file from host, now the user's host system should again give the file auto metadata.
so.. how can tails specific metadata survive through all three steps?
You're confusing filesystem metadata (such as file ownership) that lives in inodes in the filesystem, with file metadata (such as GPS coordinates) that live inside the file itself.
The former generally does not survive the process you're describing. The later survives it pretty well.
@ OP:
In a shell (konsole) try typing
man mat
This should show information about the metadata anonymization toolkit, which I know you can use to try to anonymize image file using certain formats. Not sure about videos.