fix(youtube-player): apply startSeconds with disablePlaceholder and autoplay (#32570)

Fixes a bug where the YouTube player ignored the startSeconds input when
both disablePlaceholder and playerVars.autoplay were set. The player now
correctly seeks to the specified start time using seekTo() when the video
autoplays.

The issue occurred because the code only checked the playVideo parameter
to determine if seekTo should be called, but didn't account for videos
that autoplay through playerVars.autoplay = 1.

Fixes #32545

(cherry picked from commit 0302e4b)

Author: AntonChesnokov

src/youtube-player/youtube-player.spec.ts

@@ -679,6 +679,22 @@ describe('YoutubePlayer', () => {
       expect(playerCtorSpy).toHaveBeenCalled();
     });
 
+    it('should apply startSeconds when disablePlaceholder and autoplay are both set', () => {
+      testComponent.disablePlaceholder = true;
+      testComponent.playerVars = {autoplay: 1};
+      testComponent.startSeconds = 30;
+      fixture.changeDetectorRef.markForCheck();
+      fixture.detectChanges();
+
+      // Simulate player state being PLAYING (autoplay has started the video)
+      playerSpy.getPlayerState.and.returnValue(window.YT!.PlayerState.PLAYING);
+      events.onReady({target: playerSpy});
+
+      // Should use seekTo instead of cueVideoById when player is already playing
+      expect(playerSpy.seekTo).toHaveBeenCalledWith(30, true);
+      expect(playerSpy.cueVideoById).not.toHaveBeenCalled();
+    });
+
     it('should allow for the placeholder image quality to be changed', () => {
       const placeholder = getPlaceholder(fixture);
       expect(placeholder.style.backgroundImage).toContain(

src/youtube-player/youtube-player.ts

@@ -628,11 +628,15 @@ export class YouTubePlayer implements AfterViewInit, OnChanges, OnDestroy {
         const state = player.getPlayerState();
         if (state === PlayerState.UNSTARTED || state === PlayerState.CUED || state == null) {
           this._cuePlayer();
-        } else if (playVideo && this.startSeconds && this.startSeconds > 0) {
-          // We have to use `seekTo` when `startSeconds` are specified to simulate it playing from
-          // a specific time. The "proper" way to do it would be to either go through `cueVideoById`
-          // or `playerVars.start`, but at the time of writing both end up resetting the video
-          // to the state as if the user hasn't interacted with it.
+        } else if (
+          (playVideo || this.playerVars?.autoplay === 1) &&
+          this.startSeconds &&
+          this.startSeconds > 0
+        ) {
+          // We have to use `seekTo` when `startSeconds` are specified with a playing video
+          // (either from user interaction or autoplay). The "proper" way to do it would be to
+          // either go through `cueVideoById` or `playerVars.start`, but at the time of writing
+          // both end up resetting the video to the state as if the user hasn't interacted with it.
           player.seekTo(this.startSeconds, true);
         }