If the playback was smooth for you in the past, but you've been running into issues off and on for the past month, I've noticed that packet loss has jumped tremendously starting about a month ago (at least for me), and that would definitely have a large impact on the smoothness of video playing (as well as impacting gaming if anyone in your family does that).
Starting about a month ago (again, for me at least), packet losses jumped from a once a month or so event to becoming every day / every other day at rates that are way too high (seeing packet loss above the 2.5% threshold that most people will see noticeable impact, and some days as high as 6.5% which is a big problem). A good network shouldn't go above 1% packet loss very often.