How do I capture (record) online streaming video with it's associated audio on El Capitan?

Can anyone advise or recommend which of the many different programs available I should use to capture (record) online streaming video with it's associated audio on El Capitan? I tried MacX DVD Converter Pro but believe it or not, it does not record the audio aspect of video streams. They claim there is a work-around, but after 3 days of trying various fixes, none seemed to work for me.

I tried the Safe Mode Terminal command string: csrutil disable; reboot but that didn't allow the audio capture driver from MacX DVD Converter Pro to install their System Audio driver.

I tried the sudo nvram boot-args="kext-dev-mode=1" method, but again, the playback of the recorded video was silent even though I heard the audio during the recording.

I downloaded SOUNDFLOWER but once again, I heard the audio during the screen capture, but the Quicktime playback was silent.

I can hardly believe after 3 days I'm still unable to record what I see and simultaneously hear on my screen from a streaming video such as a simple Charlie Rose interview with Martin Scorcese discussing Felini. I don't care what it costs; I just care about easy, professional, and perfect results. One of the two reasons why I BOUGHT this 27" iMac with El Capitan was so I COULD record streaming video with audio if I so choose and after a month, I still can't do it and I ran out of online help after searching dozens of websites for answers! So I now turn to the Apple Community. Thanks!

Anthony