Hello,
I am a project manager at Viddler (We use Atlassian for JIRA, but we do not use Confluence, however our customers do).
According to this page:
https://confluence.atlassian.com/display/CONF57/Widget+Connector+Examples
Support for Viddler was added in 2012 to play videos in Confluence using our flash player. We have since released an HTML5 player which our customers would like to use to embed videos in Confluence. It seems there is a need to use your Widget Connector tool rather then just a straight embed.
Is it not possible to use a straight embed code to embed html 5 video?