Interactive PDF is nothing short of a crapshoot on mobile devices. Success is highly dependent on the reader application.
What reader are you using on your iPhone? Is it Adobe Acrobat or some web browser to open the PDFs generated? If possible, please use Adobe Acrobat on your phone and see if the PDF renders properly or not.
If the issue is seen in Adobe Acrobat as well, then please share the .indd file and the PDF generated firstname.lastname@example.org so that we can investigate the issue.
But Adobe Reader on mobile devices doesn't support video! I've been complaining to the beta team about this for years!
You need to pay for a reader like PDF Expert to play video on mobile devices.
Mobile devices don't support movies in PDFs in any way. I think you will misslead the TE if you give the signal that it should do it.
I would recommend to use EPUB or Publish Online or 3rd party plugins for HTML5-export.