C#

1. The video is (sort of) displayed on top of the picturebox, so you can't get the videopicture from the picturebox. All that is used is the windowhandle of the picturebox - you could have used any type of control that exposes a windowhandle, for instance a label or a panel.
   You have to check if the ProprietarySDK (obj) exposes some method or property that returns the videopicture, otherwise the only option you have is doing a screencopy (of the picturebox area).
2. You can draw on top of the picturebox (image) but not on top of the video, again for the same reason as above: the video is displayed on top of the picturebox and thus on top of your drawing.
   
   Peter

this.pgbProgress.Dispatcher.Invoke(DispatcherPriority.Normal,
     new Action(() => { this.pgbProgress.Value += 1; }));

Luc Pattyn wrote:

That article may be fine, it doesn't seem to focus on UI handling; for WinForms all Controls should be created and handled on exactly one thread, otherwise all anomalies are possible, and a temporary or permanent hangup is most likely to occur.

var RxMouseMoveEvent = Observable.FromEventPattern<MouseEventArgs>(this, "MouseMove")
    .Select(arg=>arg.EventArgs.GetPosition(this));

RxMouseMoveEvent
    //Take it off the UI thread
    .ObserveOn(Scheduler.Default)
    // Wait for a 0.5 second pause
    .Throttle(new TimeSpan(0, 0, 0, 0, 500))
    //Do calcualtions with a function call that returns a point
    .Select(xy => CalculatePointRelateThing(xy))
    //Change it back to the UI thread
    .ObserveOnDispatcher()
    //Subscribe to the change on the UI thread
    .Subscribe(evt =>
    {
        txtText.Text = evt.ToString();
    });

Luc Pattyn wrote:

Maybe your attempt failed to correct all cross-thread violations, or OTOH your code could have a second problem on top of the UI threading one.

.Subscribe(evt =>
               {
                   if (!evt.IsCompleted)
                       Debug.WriteLine("Event Not completed");
                   else
                       Debug.WriteLine("Event completed");

                   pgbProgress.Value += 1;
                   MyStrings.Append(evt.Result.Frequency.ToString() + " Hz with the Value: " + evt.Result.Value.ToString() + Environment.NewLine);

               },
               () => {
                   txtText.Text += MyStrings.ToString();
               }
               );

Observable.Range(0, 5)
    // Take the Observable off the UI thread
    .SubscribeOn(Scheduler.Default)
    //Create parallel tasks and report results when completed
    .SelectMany(x => Task.Run<FreqValues>(() => DoTaskWork(x), ctr.Token))
    // Switch back to the UI thread
    .ObserveOnDispatcher()
    .Subscribe(args => {
        //Update the progressbar when a thread is completed
        pgbProgress.Value += 1;
        //Tell me what thread is completed
        txtText.Text += Environment.NewLine + args.Frequency.ToString();
    },
    () => {
        //All done, here I could do sorting etc.
        txtText.Text += Environment.NewLine + "All done";
          }
    );

Microsoft Visual Studio Community 2013
Version 12.0.31101.00 Update 4
Microsoft .NET Framework
Version 4.6.01038

Installed Version: Professional

namespace ANameSpace
{
    [ToolboxItem(false)]
    public partial class ValidatingBase<T> : UserControl
    {
        public ValidatingBase()
        {
            InitializeComponent();

    // and so forth

namespace ANameSpace
{
    [ToolboxItem(true)]
    public partial class PersonValidator : ValidatingBase<Person>
    {
        public PersonValidator()
        {
            InitializeComponent();

    // and so forth

Observable.Range(0, 10).
    Select(e => (Task.Factory.StartNew(() => DoWork(e),
                                            CancellationToken.None,
                                            TaskCreationOptions.DenyChildAttach,
                                            TaskScheduler.Default)))
    .ObserveOnDispatcher()
    .Subscribe(evt =>
    {
       //Do something with evt.Result
    });