Make video sprites flippable and vector-scalable to fix type constraint errors

Stable supports these on videos already from a quick read on code (since videos are generally a subclass of sprites).

osu.Game/Storyboards/Drawables/DrawableStoryboardVideo.cs

@@ -1,11 +1,16 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
+using System.IO;
+using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Textures;
 using osu.Framework.Graphics.Video;
+using osu.Framework.Utils;
+using osuTK;
 
 namespace osu.Game.Storyboards.Drawables
 {
@@ -13,7 +18,7 @@ namespace osu.Game.Storyboards.Drawables
     {
         public readonly StoryboardVideo Video;
 
-        private Video? drawableVideo;
+        private DrawableVideo? drawableVideo;
 
         public override bool RemoveWhenNotAlive => false;
 
@@ -42,7 +47,7 @@ namespace osu.Game.Storyboards.Drawables
             if (stream == null)
                 return;
 
-            InternalChild = drawableVideo = new Video(stream, false)
+            InternalChild = drawableVideo = new DrawableVideo(stream, false)
             {
                 RelativeSizeAxes = RelativeSizeAxes,
                 FillMode = FillMode.Fill,
@@ -70,5 +75,65 @@ namespace osu.Game.Storyboards.Drawables
                     drawableVideo.FadeOut(500);
             }
         }
+
+        private partial class DrawableVideo : Video, IFlippable, IVectorScalable
+        {
+            private bool flipH;
+
+            public bool FlipH
+            {
+                get => flipH;
+                set
+                {
+                    if (flipH == value)
+                        return;
+
+                    flipH = value;
+                    Invalidate(Invalidation.MiscGeometry);
+                }
+            }
+
+            private bool flipV;
+
+            public bool FlipV
+            {
+                get => flipV;
+                set
+                {
+                    if (flipV == value)
+                        return;
+
+                    flipV = value;
+                    Invalidate(Invalidation.MiscGeometry);
+                }
+            }
+
+            private Vector2 vectorScale = Vector2.One;
+
+            public Vector2 VectorScale
+            {
+                get => vectorScale;
+                set
+                {
+                    if (vectorScale == value)
+                        return;
+
+                    if (!Validation.IsFinite(value)) throw new ArgumentException($@"{nameof(VectorScale)} must be finite, but is {value}.");
+
+                    vectorScale = value;
+                    Invalidate(Invalidation.MiscGeometry);
+                }
+            }
+
+            protected override Vector2 DrawScale
+                => new Vector2(FlipH ? -base.DrawScale.X : base.DrawScale.X, FlipV ? -base.DrawScale.Y : base.DrawScale.Y) * VectorScale;
+
+            public override Anchor Origin => StoryboardExtensions.AdjustOrigin(base.Origin, VectorScale, FlipH, FlipV);
+
+            public DrawableVideo(Stream stream, bool startAtCurrentTime = true)
+                : base(stream, startAtCurrentTime)
+            {
+            }
+        }
     }
 }