Adjust bitrate of Video - Works for some not all

[chuck217]

Happily running 6.1.beta2 (build dc75a2) – March 23, 2017 and just noticed that I am able to select the bitrate while watching a video which is great because sometimes outside my network I don't have enough bandwidth to stream movies - I've noticed this dropdown pops up for some of my movies and not others, specifically mp4's .. I have looked in Settings but have not found any transcode settings specifically for Video -- Any help would be appreciated

Thanks
Chuck