The following is the info from running the xfinity diagnostics after the error code. Here's some addition info: I'm running 55.0a1 () (64-bit) The only add-on that gets automatically loaded on this nightly is the Norton Security Toolbar, since I have the customer provided Comcast Norton Security Suite installed. I just tried the latest Firefox developers edition nightly 54a2 64bit () and the recorded content does NOT work for me. Loading of the specified resource has failed We've run into a problem while streaming Shockwave. Using the other browsers the CPU usage on the same content to about 50%. Also on my Core2Duo 2.4ghz laptop (Nvidia 9600M)the performance of playing live content from Xfinity is very poor with consist jerkiness in the playback with the CPU usage at around 100%. It seems to be related to Adobe Flash's interaction with Firefox 64bit, since the recorded content plays fine on Edge, Chrome and IE and Firefox 32bit.