I have 120mbs download internet and Ultraflix runs perfectly. Even when I had only 20mbs download it ran perfectly. I cannot say the same for the other 4k streams I have tried to watch. They run fine for 5 minutes and then buffering starts even at 120mbs. Anyone hinting that Ultraflix buffers is lying as far as I am concerned. The "Secret Sauce" runs perfectly and without lessening the quality.