Android MediaPlayer - how to render video file to texture over background texture from camera?

Question

Android

Hello everyone, I'm making a simple application: an object (Vuforia User Defined Target) is detected in a running AR session, a surface is attached to it, into which an external video should be rendered. Everything is fine with detection, but a frame from the camera is rendered instead of a frame from the video file. In principle, Vuforia does not seem to depend much here, so the question can be abstracted from it.

Here is the media player initialization code:

videoPlayer = MediaPlayer()
        videoPlayer.setSurface(mRenderer?.planeSurface)
        videoPlayer.isLooping = true
        val afd: AssetFileDescriptor
        try {
            afd = assets.openFd("test.mp4")
            videoPlayer.setDataSource(afd.fileDescriptor, afd.startOffset, afd.length)
            videoPlayer.prepare()
            videoPlayer.start()
        } catch (e: IOException) {
            e.printStackTrace()
        }

Here is the texture initialization code:

GLES20.glGenTextures(1, planeSurfaceTextureId, 0)
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, planeSurfaceTextureId[0])
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR)
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR)
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE)
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE)
        planeSurfaceTexture = SurfaceTexture(planeSurfaceTextureId[0])
        planeSurfaceTexture.setOnFrameAvailableListener(mActivity)
        planeSurface = Surface(planeSurfaceTexture)

Here is the actual rendering of the surface with the frame:

planeSurfaceTexture.updateTexImage()
        GLES20.glActiveTexture(GLES20.GL_TEXTURE1)
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, planeSurfaceTextureId[0])
        GLES20.glUniformMatrix4fv(mvpMatrixHandle, 1, false, modelViewProjection, 0)
        GLES20.glUniform1i(texSampler2DHandle, 0)
        GLES20.glDrawElements(GLES20.GL_TRIANGLES, contentPlane.numObjectIndex, GLES20.GL_UNSIGNED_SHORT, contentPlane.meshIndices)
        GLES20.glDisableVertexAttribArray(vertexHandle)
        GLES20.glDisableVertexAttribArray(textureCoordHandle)

I can show you the whole code if needed.
I'm new to android, maybe some kind of stupid mistake, please help me figure it out :) Maybe here you can do without GLES at all.

Thanks in advance!