I`m having problems with 2 browsers in W10. When I watch video from websites using IE, about every few minutes the video will freeze up for a few seconds, then resume. What settings in IE or W10 do I need to check to fix this issue?

Using Firefox, watching video from the same website, the video size is too small. You can see the box where the video size is supposed to fill normally, but currently the video size is only a quarter of what it normally should be.
What settings in Firefox or W10 will fix this?

I contacted technical support of the business that airs the video, and they said it my browser settings.