Hi,
without example URLs and a log or maybe even access to such a video and a Facebook account there is no way to tell why this happens - I can promise it's not on purpose.
There are multiple reasons why this may happen:
1. The video in question is only available in their "MPD" format --> JD cannot download this and instead does a fallback to the highest available http quality --> Could be low quality.
2. Bug in our plugin.
To check for MPD, you could e.g. try the
manual download method and find out in which format this content is streamed.
-psp-