Hi everyone. I am having the exact same issue with the latest Netflix app. I just got off the phone with customer support and they were absolutely no help at all. They asked me questions about my phone display settings, app display settings, etc. Even asked me if my brightness setting was turned all the way up right after I told them that my brightness setting was turned all the way up LOL. Anyway, their "resolution" was to use the browser. Give me a break.
Anyway, i downloaded the APK for version 4.12.2. This absolutely resolved the issue. Videos are bright as can be. So if you are having this issue, I suggest you bite the bullet, uninstall the previous version (for now) and find the APK. I don't want to post a link to an APK in case it doesn't work with your phone. However, do a simple search for "Netflix 4.12.2 APK" and you will find it.
I hope this helps someone...thanks!