Version History is an integral part of any asset management system. You might want to update a template; edit a video without resetting all of its permissions; or have your latest slides handy, without losing access to the previous version. In all these cases - Version History is the solution.
From the Asset Preview page, use the button at the top of the page [#1 in the image below] to upload a new version of the file.
After updating the file, all previous tags, collections, comments, and other data will remain - only the file itself will change.
You can view or restore previous versions from the bottom of the detail section [#2 in the image]
Note that versioning only works for uploaded files, and not for saved links.