Been watching a lot of Sky Sports with Boost this weekend. Why can't NoWTV even with Boost at 50fps track horizontal movement cleanly? Microjuddering plain to see especially with pitch patterning.
What platform are you watching on? Laptops, Desktops, Tablets and Phones will be 60Hz usually, so will show 10Hz micro juddering on 50Hz motion as one frame in 5 will be repeated to get from 5 frames to 6, and thus from 50->60Hz. (It may also be possible for you to configure a NowTV box to output 60Hz, not 50Hz, too?)
If you are watching at 50Hz and still seeing judder, then that suggests they may have issues in deinterlacing their 1080i25 sources to 720p50 or 1080p50. (The nature of interlace on 50Hz native content is that there is motion between the two fields within an interlaced frame - and you have to trade-off vertical resolution with >25Hz motion in the deinterlacing process. Some adaptive deinterlacers can fail nastily in some situations.)