Have to tried to play and video from assest folder of apk ??
almost 10 years ago
As it is right now the AR.context.startVideoPlayer method is aimed at displaying videos from external URLs that reside on an external webserver. For local resources as in your case in the assets folder this might cause some problems.
So if that constitutes a possibility for you, the fastest way for you would be to load your video file on a webserver and use that as input for the AR.context.startVideoPlayer method.
Another maybe more flexible solution would be to write your own VideoPlayer activity in java and design it upon your needs. As this activity only consists of a few components this task should not be to lengthy. The ApiDemos project that ships with your Android SDK (Path: YOUR_ANDROID_SDK_FOLDER/sdk/samples/API_LEVEL/ApiDemos) should give you a very good starting point to quickly complete that task. Specificly the MediaPlayerDemo_Video.java and VideoViewDemo.java classes should be very helpful.
As an example, in your ARchitect world you could then write