Dear Aworan, thank you so much for this Tutorial, with the information and steps contained here i was able to get Netflix and Amazon video up and running this evening in Chromium 50 and it works remarkably well. For anyone else looking to get this up and running as of today, i would suggest to follow Aworan’s guide’s almost exactly, but with the below minor modifications.
First install Chromium 50 as per Aworan’s guide;
ubuntu-mate.community/t/tutorial-install-working-chromium-50/6762
In the next Tutorial
Install opengl driver and chromium
sudo rpi-update at the moment provides an opengl driver that will give a blank screen, (although i haven’t tried today#s 4.4.21 yet) so using sudo BRANCH=next rpi-update i went back to 4.4.17-v7+ And tried various Kernels in between, depending on your over-clocking settings, if you use them i found this to be reasonably stable and atm imo the best option. There does seem to be an issue with HDMI sound out so i had to run sudo amixer cset numid=3 1 and currently use the 3.5 jack, but it’s a small price to pay for hardware acceleration. Apart from that just follow along the tutorial.
For the Tutorial [Tutorial] - Chromium & Youtube in 720p (and other videos websites) the only thing i would mention in relation to Netflix / Amazon video, is that you will need to go back into chrome://flags and re-enable Media Source API Netflix looks for this otherwise it will give a blank screen, Amazon probably does too but i haven’t checked.
Once you’ve done all that we would come to step 2;
Step 2 : Get widevine librairies from a chromebook image and copy it to chromium directory
The download url wget https://dl.google.com/dl/edgedl/chromeos/recovery/chromeos_7077.134.0_daisy-skate_recovery_stable-channel_skate-mp.bin.zip - today by continuing with the other steps this would provide libwidevinecdm which is out of date and trying to watch Netflix will provide some bunch of letters and numbers as an error code and on Amazon they will tell you it is unsupported and to go away and come back when you have bought some Amazon Fire Tablets or sticks…, or words to that effect.
So we need a more up to date recovery image the below should work
The only other line that we have to of course change is the sudo kpartx to reflect the new bin
sudo kpartx -av chromeos_7834.60.0_daisy_recovery_stable-channel_snow-mp-v3.bin
There is a sneaky missing letter r in the line cd /tmp/chomeos/opt/google/chrome/ so it should be cd /tmp/chromeos/opt/google/chrome/ , but i think Aworan did that on purpose to confuse stupid people like me 
Everything else including the user agent is exactly as Aworan has outlined. So once again many thanks Aworan.
If i have forgotten anything, let me know, i wanted to reply while it was still fresh in my mind
Thanks