How to reproduce:
1. Open the attached project
2. Open Build settings and make sure that Development build and Autoconnect profiler are enabled
3. Build and run test scene on Galaxy S III Mini
4. Connect profiler to a device
5. Type VideoPlayer. in profiler search field so all visible events would be useful for this case
Result: it is obvious that on device performance is pretty bad and you can see some spikes in the profiler for VideoPlayer.Update event which sometimes reach ~16 ms.

Note: surfaceTexture->updateTexImage() does not have separate profiler entry, but gets accumulated in VideoPlayer.Update profiler time. This time varies depending on video resolution, so bigger resolution videos frame rate is greatly reduced, this should be filed as another bug.

Reproducible:
2017.3.0b3 at most it took 16ms
2017.2.0f2 at most it took 8ms

Device:
42, Samsung [GT-I8200N], 4.2.2, 480x800, GC1000

After latest changes 2018.2: Now occasional spikes in profiler are caused by waiting for data to decode, so video player is working as expected on this device.