HD Video in Unity 3D

We are creating a 3D touchscreen experiential kiosk system using Unity3D and we want to display an HD video as part of it (the video needs to be HD because it is being displayed on a very large touchscreen).

All the different encoding options and importing sequences we have tried lead to choppy playback. Is there a known fix for this or is this just a limitation of Unity3D and large dimension videos (1920 x 1080 in our case)

Thanks in advance if anyone does have a fix.