specifically-slower YT download speeds

Welcome from another Mac user.

If it's just YouTube, it's possible it could be an upstream problem with HughesNet's provider (Level3, Qwest, or other) or it just could be DNS-related routing problem. Rebooting everything (modem, router and computer) and see if it shakes loose.

If it persists after that, you might want to open a terminal window and type "traceroute youtube.com" to see where the possible roadblock is.

Edit: Just another thought, you might want to try different combinations of turning the Video Data Saver and Web Acceleration on and off and see if that makes a difference as well.

Yeah, this sounds like a Video Data Saver thing...  Hughesnet will automatically throttle speeds to various streaming sites to help force SD playback to save users data.  You can disable this feature.

You can view more information including how to disable the Video Data Saver option here: Video Data Saver FAQ

 It's a fairly new feature that was introduced with Gen5 service plans, but, Gen4 plans have also been upgraded to include the Video Data Saver feature in the last month or two.

C0RR0SIVE, ah that makes perfect sense then and YES, thanks to you both, that worked like a charm!  I rebooted and turned off the video saver button.