Clarify how to play videos in Dome Viewer on Quest

[hybridherbst]

Currently, when using the Quest Dome Viewer app, one needs to either

1. copy your video files to Quest, or
2. use an NDI-capable sender on your local network.This can for example be VLC Media Player (there's an NDI sending plugin for it), or OBS, or Premiere (which also has an NDI plugin).

We should document this better to make it easier for people to play back videos.

[joshuakery]

Could you please clarify exactly what the controls are on the Quest in a simple comment here?

After launching the Quest app, I have no idea how to select an NDI input or video on the device. Presumably, for (1), the videos go in the two folders in StreamingAssets. But how do I get things on the model?