I've gotten complaints similar to this recently. I don't know what your streaming platform is, but I believe that Youtube (which is what we use) is beginning to drop it's support of the antiquated 'Flash' platform. Indeed Flash is no longer being supported, and is a potential security threat to computers. The people in question should make sure they update their browsers to the latest version to be able to support html5.
The comments I have gotten are from people trying to use smart tv's Youtube app, a similar solution should help them as long as the TV's manufacturer has a firmware update that supports html5 video.