Suppress copy_from_video flakes

No-Try: true
Bug: 408486529, 408556424
Change-Id: I0fb4f2636382840c508519783e84faadfa66f22d
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/235054
Auto-Submit: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/webgpu-cts/expectations.txt b/webgpu-cts/expectations.txt
index 9b3f8fc..1cd118e 100644
--- a/webgpu-cts/expectations.txt
+++ b/webgpu-cts/expectations.txt
@@ -325,8 +325,10 @@
 # Flaky on Mac SwiftShader
 crbug.com/40853211 [ mac webgpu-adapter-swiftshader ] webgpu:web_platform,copyToTexture,canvas:copy_contents_from_bitmaprenderer_context_canvas:* [ RetryOnFailure ]
 
-# Flaky on Linux SwiftShader
-crbug.com/40853211 [ linux webgpu-adapter-swiftshader ] webgpu:web_platform,copyToTexture,video:copy_from_video:* [ RetryOnFailure ]
+# Flaky on Linux (with SwiftShader)
+crbug.com/408486529 [ linux webgpu-adapter-swiftshader ] webgpu:web_platform,copyToTexture,video:copy_from_video:* [ Failure ]
+# Flaky on Linux (with VVL)
+crbug.com/408556424 [ linux dawn-backend-validation ] webgpu:web_platform,copyToTexture,video:copy_from_video:* [ Failure ]
 
 # Failing on SwiftShader on various platforms
 crbug.com/407814992 [ mac webgpu-adapter-swiftshader ] webgpu:web_platform,canvas,readbackFromWebGPUCanvas:transferToImageBitmap_huge_size: [ Failure ]