Looks more like a restriction in FM Go/iOS:
FileMaker Go doesn’t support:
1 the Inspector Data Formatting options Images or Interactive content. (Content in container fields is displayed by the iOS like other iOS audio, video, and PDF files.) "
page 10 of the fm_go development.pdf
Thank you, Jade. I did see that but may have misunderstood it. YouTube videos, for example, auto playback in browsers on iPads, but not in container fields in FM GO set for auto play back. Does this seem inconsistent?