Add widget of the week videos (flutter#116451)

(and remove one video that was listed twice with the same widget)

Author: tvolkert

packages/flutter/lib/src/material/autocomplete.dart

@@ -12,6 +12,8 @@ import 'theme.dart';
 
 /// {@macro flutter.widgets.RawAutocomplete.RawAutocomplete}
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=-Nny8kzW380}
+///
 /// {@tool dartpad}
 /// This example shows how to create a very basic Autocomplete widget using the
 /// default UI.
@@ -26,8 +28,6 @@ import 'theme.dart';
 /// ** See code in examples/api/lib/material/autocomplete/autocomplete.1.dart **
 /// {@end-tool}
 ///
-/// {@youtube 560 315 https://www.youtube.com/watch?v=-Nny8kzW380}
-///
 /// See also:
 ///
 ///  * [RawAutocomplete], which is what Autocomplete is built upon, and which

packages/flutter/lib/src/painting/gradient.dart

@@ -336,6 +336,8 @@ abstract class Gradient {
 
 /// A 2D linear gradient.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=gYNTcgZVcWw}
+///
 /// This class is used by [BoxDecoration] to represent linear gradients. This
 /// abstracts out the arguments to the [ui.Gradient.linear] constructor from
 /// the `dart:ui` library.

packages/flutter/lib/src/painting/text_style.dart

@@ -38,6 +38,8 @@ const double _kDefaultFontSize = 14.0;
 
 /// An immutable style describing how to format and paint text.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=1z6YP7YmvwA}
+///
 /// ### Bold
 ///
 /// {@tool snippet}

packages/flutter/lib/src/widgets/actions.dart

@@ -585,6 +585,8 @@ class ActionDispatcher with Diagnosticable {
 /// A widget that establishes an [ActionDispatcher] and a map of [Intent] to
 /// [Action] to be used by its descendants when invoking an [Action].
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=XawP1i314WM}
+///
 /// Actions are typically invoked using [Actions.invoke] with the context
 /// containing the ambient [Actions] widget.
 ///

packages/flutter/lib/src/widgets/async.dart

@@ -447,6 +447,8 @@ class StreamBuilder<T> extends StreamBuilderBase<T, AsyncSnapshot<T>> {
 /// Widget that builds itself based on the latest snapshot of interaction with
 /// a [Future].
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=zEdw_1B7JHY}
+///
 /// The [future] must have been obtained earlier, e.g. during [State.initState],
 /// [State.didUpdateWidget], or [State.didChangeDependencies]. It must not be
 /// created during the [State.build] or [StatelessWidget.build] method call when

packages/flutter/lib/src/widgets/basic.dart

@@ -7465,8 +7465,6 @@ typedef StatefulWidgetBuilder = Widget Function(BuildContext context, StateSette
 ///
 /// {@tool snippet}
 ///
-/// {@youtube 560 315 https://www.youtube.com/watch?v=syvT63CosNE}
-///
 /// This example shows using an inline StatefulBuilder that rebuilds and that
 /// also has state.
 ///

packages/flutter/lib/src/widgets/focus_scope.dart

@@ -12,6 +12,8 @@ import 'inherited_notifier.dart';
 /// A widget that manages a [FocusNode] to allow keyboard focus to be given
 /// to this widget and its descendants.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=JCDfh5bs1xc}
+///
 /// When the focus is gained or lost, [onFocusChange] is called.
 ///
 /// For keyboard events, [onKey] and [onKeyEvent] are called if

packages/flutter/lib/src/widgets/shortcuts.dart

@@ -872,6 +872,8 @@ class ShortcutManager with Diagnosticable, ChangeNotifier {
 /// A widget that creates key bindings to specific actions for its
 /// descendants.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=6ZcQmdoz9N8}
+///
 /// This widget establishes a [ShortcutManager] to be used by its descendants
 /// when invoking an [Action] via a keyboard key combination that maps to an
 /// [Intent].