They used to require DTube be the first tag but that is no longer the case. You can use DTube but make sure openmic is the first tag and you need to embed a YouTube or Vimeo link in your post as well.
This is clearly explained more than once on every Open Mic post under the rules

There it is on the last part of the list of rules
- Even if you use DTube a YouTube or Video link must be added to your post too
I don't know how to make it any clearer than that.
Undertood. Thank you for clarifying.