I think it should be handy enough to use. Most of the screen recorder programs are fairly intuitive.
However, that is the pro version which means you have to pay for it, which kind of defeats the whole purpose of our endeavour to get things for free here, lol.
Also, I would have reservations about whether a screen record of a video would truly be akin to source quality.
With all that said, I took a punt and purchased Tubedigger.
I can confirm that it does capture DRM videos in REC Mode in full with sound.
However, you do of course have to watch the video in full while it captures and also, I'm only getting 1 MB/s download speed, so perhaps that's a security feature on OF?
I have posted the metadata from the video I downloaded below if anyone would like to check it and see if it looks like source quality.