TubeDigger 1.4.1 d/l from ur site works really well.
The Rec On/Rec Off is confusing. Seems to need a status indicator. I had to guess that if the "Rec On" button is available, I'm in "Rec Off" mode. I may even be wrong about that.
At this point TubeDigger, don't change much. I'm afraid you'll fall victim to feature creep and the UI will become worse and the program will suffer.
Don't go nuts with converting options. What you have is fine. Quality looks good. I use CL FFMpeg myself.
Give me some time to see if this stays working as sites become aware of it. If it keeps working I'm a buyer.
Great job!