VideoViewModel.cs

    public class VideoViewModel : ViewModelBase
    {
        public RelayCommand Navigate { get; private set; }

        public string DownloadUrl
        {
            get { return _video.DownloadUrl; }
        }
        public string Title
        {
            get { return _video.Title; }
        }

        public string Duration
        {
            get { return "Duration:" + _video.Duration + "secs"; }
        }

        public string Description
        {
            get { return "Description:" + _video.Description; }
        }

        public string ImageUrl
        {
            get { return _video.ImageUrl; }
        }

        public string Authors
        { ... }

        .....
    }
}