Process AVAsset to upload video to server

I have built up a list by getting the files of type video from a custom album as shown below. No problems there.

foreach(var asset in PHFetchResult)
{
    manager.RequestAvAsset(asset, videoOptions,
                (video, optionParams, handler) =>                     
                    {          
                        fileName = asset.ValueForKey((NSString)"filename");
                        videos.Add(video);  //List<AVAsset> (this is filtered by: asset.MediaType == PHAssetMediaType.Video)                        
                    });
}

What I need to understand is what to do with them next, as I want to upload them to a server.

With images, I can just do UIIMage.AsPNG, add that into a Stream and send it off to the server.

Could someone please give an example of the process with video files?