[OPIK-3385] [FE] Fix video previews not loading in playground

[YarivHashaiComet]

Details

This PR fixes video thumbnails not displaying in the playground dataset table when using cross-origin video URLs (e.g., S3 URLs).

Root Cause

The VideoThumbnail component was attempting to use HTML5 canvas to extract video frames for thumbnail generation. This fails for cross-origin videos due to CORS restrictions - browsers block pixel-level access to cross-origin media when using canvas (known as "tainted canvas").

Solution

For cross-origin videos, the component now:

1. Detects if the video URL is cross-origin using the isCrossOrigin() helper
2. Skips canvas-based thumbnail generation entirely
3. Uses ReactPlayer directly to display the video, which can play cross-origin videos without needing pixel access

For same-origin videos, the existing optimized canvas-based thumbnail generation continues to work.

Benefits

• ✅ Video thumbnails now display properly for cross-origin URLs
• ✅ No more CORS errors in the console
• ✅ Better performance - skips failed thumbnail generation attempts
• ✅ Works in playground dataset tables, tooltips, and fullscreen dialogs

Change checklist

• User facing
• Documentation update

Issues

• OPIK-3385

Testing

Tested with S3 video URLs in the playground:

1. Load dataset with video URLs in playground
2. Video thumbnails display correctly in the dataset table
3. Clicking on videos opens fullscreen player
4. No CORS errors in console

Documentation

N/A

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• URL: https://pr-4374.dev.comet.com
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• Namespace: pr-4374
• Version: 1.9.41-4374-merge-660
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[awkoy]

Great work!