To repro:
1) Open attached project
2) Build and run on a Asus K011 device

Expected result: a video can be seen on the screen
Actual result: Only the sound can be heard comming from the device

Note: This uses the new VideoPlayer. Also, the source video itself can be viewed on the device (when not using unity to stream it)

Devices Under Test
Reproduces
E5OKCY538221 x86 Intel/BayTrail 800x1280 4.4.2 31% 15h Asus K011*
Does not repro
F7NPFX236589 x86 Mali-450 MP 600x1024 5.0.2 100% 39h Asus P01Z*
HT77E1A00039 arm64-v8a Adreno (TM) 540 1080x1920 8.0.0 81% 23h Google Pixel 2*
0421415601818002f555 armeabi-v7a NVIDIA Tegra 1200x1920 6.0.1 45% 0h Nvidia SHIELD Tablet*
479000d617a23200 armeabi-v7a Vivante GC1000 480x800 4.2.2 95% 528h Samsung GT I8200N*
ce061716c3c00a40017e arm64-v8a Mali-G71 1440x2960 7.1.1 100% 9h Samsung SM N950F*
2740dab2 arm64-v8a Adreno (TM) 405 1080x1920 5.0.2 100% 163h Xiaomi Mi 4i*

reproduces on:
2017.1.0f3, 2017.2.0f3, 2017.3.0.b11, 2018.1.0a1, 2018.1.0a6 (to test on 2018.1a5 or newer you need to delete android:icon="@drawable/app_icon from AndroidManifest.xml)

note: On 2017.1.0f3 a blue screen can be seen, as opposed to black screen on other devices.
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Fixed in: 2018.3.0a1