I'm able to stream Netflix, Hulu, and Amazon Prime most of the time, unless there's a lot of congestion (which happens sometimes in the evenings). Keep in mind though, that while this can be done, it's more challenging on satellite because the broadband is limited and satellite internet has a lot of latency (due to the laws of physics, so the latency can't be reduced with current technology).
You can cancel any time, but after the system has been installed, you'd have to pay an early termination fee, which comes to $400 for the first 90 days. Then it reduces by $15 every month.
*I am not a Hughesnet employee or representative. This is a customer-to-customer tech support community, and I am a customer.
If you are trying to stream in anything higher than 480p, you'll most likely need to turn off, or snooze, the Video Data Saver.
Keep in mind that streaming is a data intensive activity, especially when done in HD. Netflix's data amounts state 300MB per hour in LD, 700MB per hour in SD, and 3GB per hour in HD.
Also, during the first twenty days your HughesNet service is in what's known as a "relaxed bandwidth state", meaning that your monthly data allotment is continually reset during this time. HughesNet does this as a courtesy in order to allow new customers to update/upgrade their devices to current without it affecting what would be their normal monthly data allotment, as those activities can use a LOT of data, especially if the devices haven't been connected to the internet in a while. After the twenty days the continual data resets will end and the data you use will be counted like it normally would. The relaxed bandwidth state is mentioned in the Welcome email sent by HughesNet, but I mention it here because people often don't notice, or bother to read, the Welcome email.