I also am experiencing this since I downloaded Windows 8.1 with Internet Explorer 11 (originally had W8).
I have the latest Adobe Flash Player installed per Adobe's website verifying it.
Since the W8.1 update I can no longer view many online videos and tv sites that I previously were able to with no problem.
I am discovering many people are discovering this problem after they download the W8.1 upgrade.
What is your operating system? What is your browser?
I am using Windows 7 and IE 10. Thank you.