I would check Adobe's
Flash site to confirm if you are running an updated version? It's a browser security issue, as Flash has become a favorite hacker access tool exploiting player vulnerabilities. As a result, Firefox blocks outdated Flash versions, requiring you manually enable it, taking the risk associated with doing so. Chrome auto updates Flash as part of their browser updates.
I had no issues running CNBC videos in Firefox with both Adobe DRM plugin enabled or even disabled, so not sure what issue you are having? It doesn't appear they are using DRM?
Some possibilities include corrupt Firefox code base, or some type of browser malware?