NOTE: The following changes will only work on Android devices that use a...

...n updated CLI that includes task CLI-323 (currently PRed with SHA 3b16e546aae0d16041ceb15abdfa8e77ad4db2df)

Added Video.RootFolder const along with documentation to help users know that their videos must be located in ‘assets/videos/‘ in order for them to work on Android.  Android Video Playback checks that the supplied path starts at ‘assets/videos/‘ and if it doesn’t, it early out fails with the proper error message.  Updated VideoExample project to match these changes.