Sound does not work in Appian Academy lesson Create an Application: First Steps

The video sound does not work in Appian Academy lesson Create an Application: First Steps.

Tried Chrome and Firefox but that did not fix the problem.  Sound works fine in both browsers 

for non-Appian websites. 

Sent multiple emails to 'academy@appian.com' and received  auto-response  emails only.

But sound has not been fixed and have not received any communications other than

the auto-response emails.

Suggestions on fixing the source so I can use the Applian Academy lessons?

Thanks for the help.