Thanks for writing in!
Integrity, Ethos, Renew and Icon are stacks which were built in the theme. You can switch between these stacks in X > Theme Options > Stack.
To resolve your portfolio featured video, please review more about the portfolio, the portfolio items and how you can properly set this. Perhaps this article could help you:
For more tutorials in using X theme, you can always check out our knowledge base: https://theme.co/apex/forum/t/knowledge-base-overview/287
Or check out this youtube channel: https://www.youtube.com/watch?v=G0euRs7SSZY&list=PLsBoF66x4ZmDqD5UBzUTZ8wFhu9yz8hBr
Hope this helps.