The video player of Vimeo, Youtube and at least one other player behave differently in the hybrid app on Android, compared to the mobile browser (tested Chrome). The full screen button is hidden in the hybrid app, while it is not on the mobile browser.
So somehow the hybrid app is causing this behavior. Someone else tested this as well, appearantly the full screen button is present on Android tablets, it's just not working (don't have a tablet to test this).
Interestingly, the creative captions button can be made visible (see screenshot)
EDIT: I did some more testing. On a different authoring tool (Storyline 360), I added a Youtube video as web component. Again, the full screen button is not there. (http://imgur.com/a/DqQeP )
When a youtube video is added in the course description, the full screen display is visible (http://imgur.com/a/A218v). So it looks like it is only disabled in the SCORM player of the Moodle Mobile app.