One of the most common causes of videos not appearing once embedded is a conflict of web protocols.
Two of the most common protocols you’ve most likely seen are “http” and “https”. If the page web page displayed in the address bar is “https,” all content on that page must be delivered via an https protocol (i.e. securely), otherwise your browser will block the insecure (http) content.
Look at your browser’s address bar. If you see something like this (https:), you may be encountering a security error.
Ensure all urls in the embed code as well as within the HapYak project itself (videos, pictures, css/js links, etc), are structured with two forward slashes "//" preceding the urls. Leaving off the protocols http or https will allow your browser to interpret the http/https protocol as needed.
Remove the protocol and its colon from the url
Current URL Protocol-less URL