diff --git a/src/server/chromium/crPage.ts b/src/server/chromium/crPage.ts
index 75bb585085..e08fdda7f8 100644
--- a/src/server/chromium/crPage.ts
+++ b/src/server/chromium/crPage.ts
@@ -404,11 +404,11 @@ class FrameSession {
 
     let screencastOptions: types.PageScreencastOptions | undefined;
     if (this._isMainFrame() && this._crPage._browserContext._options.recordVideo && hasUIWindow) {
-      const size = this._crPage._browserContext._options.recordVideo.size || this._crPage._browserContext._options.viewport || { width: 1280, height: 720 };
       const screencastId = createGuid();
       const outputFile = path.join(this._crPage._browserContext._options.recordVideo.dir, screencastId + '.webm');
       screencastOptions = {
-        ...size,
+        // validateBrowserContextOptions ensures correct video size.
+        ...this._crPage._browserContext._options.recordVideo.size!,
         outputFile,
       };
       await this._crPage._browserContext._ensureVideosPath();
diff --git a/src/server/firefox/ffBrowser.ts b/src/server/firefox/ffBrowser.ts
index f3f247404d..e3314d0075 100644
--- a/src/server/firefox/ffBrowser.ts
+++ b/src/server/firefox/ffBrowser.ts
@@ -194,10 +194,10 @@ export class FFBrowserContext extends BrowserContext {
     if (this._options.colorScheme)
       promises.push(this._browser._connection.send('Browser.setColorScheme', { browserContextId, colorScheme: this._options.colorScheme }));
     if (this._options.recordVideo) {
-      const size = this._options.recordVideo.size || this._options.viewport || { width: 1280, height: 720 };
       promises.push(this._ensureVideosPath().then(() => {
         return this._browser._connection.send('Browser.setScreencastOptions', {
-          ...size,
+          // validateBrowserContextOptions ensures correct video size.
+          ...this._options.recordVideo!.size!,
           dir: this._options.recordVideo!.dir,
           browserContextId: this._browserContextId
         });
diff --git a/src/server/webkit/wkPage.ts b/src/server/webkit/wkPage.ts
index 18e2927ee6..5adf305383 100644
--- a/src/server/webkit/wkPage.ts
+++ b/src/server/webkit/wkPage.ts
@@ -116,11 +116,11 @@ export class WKPage implements PageDelegate {
         promises.push(this._grantPermissions(key, value));
     }
     if (this._browserContext._options.recordVideo) {
-      const size = this._browserContext._options.recordVideo.size || this._browserContext._options.viewport || { width: 1280, height: 720 };
       const outputFile = path.join(this._browserContext._options.recordVideo.dir, createGuid() + '.webm');
       promises.push(this._browserContext._ensureVideosPath().then(() => {
         return this._startScreencast({
-          ...size,
+          // validateBrowserContextOptions ensures correct video size.
+          ...this._browserContext._options.recordVideo!.size!,
           outputFile,
         });
       }));