With google sites, or any site that does not fully recognize html, the
page tends to cut off some of the code. There should be an "edit
html" button within the designer view. This icon looks like a pencil
with "html" beside it. Click on that link and a new box will pop up
allowing you to see the page code, here you can just paste the video
embed code wherever you think it belongs and click preview before
saving to make sure the video appears where you'd like it to. This
process may look different on each site, and sometimes you may have to
view the raw html source code to be able to input the embed code
correct.
- Clayton Bryan