While TubePress is not currently enabled for Wix mobile websites, we expect to be fully enabled at any moment.
Wix's QA team has to approve each app's mobile support before it gets the cool green "Mobile ready" banner in the app store. Before an app is approved, it won't show up in the mobile website view. We submitted TubePress for review earlier this week. They gave us an initial thumbs up, so we should get the official green light very shortly.
I'll post back here when we have more news, or feel free to simply keep checking in at Wix. Thanks!