I am only double posting because I solved this, and I figured if anyone was curious, they would like to know.

Instead of a call back, which can be called at any time (which I assume will mostly be AFTER a frame is rendered and before it is cleared, thus not rendering, I used this in my render loop.

			if(player.IsPlaying)
			{
				Bitmap bitmap = memRender.CurrentFrame;
				BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
					ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
				GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, data.Width, data.Height, 0,
					OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0);
				bitmap.UnlockBits(data);
				bitmap.Dispose();
			}
			base.OnRenderFrame(e);

it is playing the video just fine, although I am not sure how to handle multiple textures yet.

also is there a more efficient way of doing this?

I am only double posting because I solved this, and I figured if anyone was curious, they would like to know.

Instead of a call back, which can be called at any time (which I assume will mostly be AFTER a frame is rendered and before it is cleared, thus not rendering, I used this in my render loop.

int width = 0;
		    int height = 0;
		    if(player.IsPlaying)
		    {
			    Bitmap bitmap = memRender.CurrentFrame;
			    BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
				    ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
			    GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, data.Width, data.Height, 0,
				    OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0);
			    bitmap.UnlockBits(data);
			    bitmap.Dispose();
			    width = data.Width;
			    height = data.Height;
		    }
		    base.OnRenderFrame(e);

it is playing the video just fine, although I am not sure how to handle multiple textures yet.

also is there a more efficient way of doing this?