vimeo video

These tests show that when a video from a hosting site such as is embedded in a Google site, the full-screen option does not appear.

YouTube videos inserted using Insert>YouTube will have the full-screen option.

Google has been asked about this but the situation has not changed.

Embed gadget

Include gadget (iframe)

MVI_0160 from Bob Wilcox on Vimeo.

xml gadget

The full-screen option works when it is embedded into a site hosted elsewhere such as

But when that video is iframed into this site there is no FS option. 

Include gadget (iframe)