I'm on Win10 StreamFab 5.0.1.8
I never downloaded from PBS.org before but the Youtube Downloader just worked great for me for a PBS.org video.
I did it in the following steps.
1. Logged into PBS.org with my Chrome browser, navigated to the video, copied the video link.
2. Logged into StreamFab chose Youtube on the left, then Youtube on the right that was under "Popular sites"
3. Erased the link address at top in Youtube and pasted the link from my Chrome browser that I copied (didn't do any logon or navigating in StreamFab)
4. Noticed that the box that popped up for video had blank in Audio and none in subtitle (I will attach screenshot of another file to show you what I mean)
5. Added to Queue anyway
6. Downloaded & it plays great.
Mike_M
Once you have added the first episode of a PBS series this way, you can simply go down that PBS page, click on the next episode and you will get the pop-up box which allows you to download additional episodes.
Also if you click on the "None" subtitle box, it gives you the option to click a box marked "sub'. I don't know if you need to do that to get subs, but if you do, they show up.