How did we fix this?
Post Custom Field > Video > is not set
Conditionals don’t work with the Metabox Themer Connector! You have to use the Core WordPress Custom Field Connection that comes with Themer when chacking against metabox oEmbed fields. The metabox shortcode always spits something out, but using the basic post custom field method checks if there is a value in the field.
Check out what we did on Clapham Blog: