How to block YouTube’s annoying and pointless new animated ‘thumbnail previews’ of videos in the search-results.

1. Open your uBlock Origin browser ad-blocking addon.

2. Go to uBlock’s “My Filters” tab.

3. Add …

…to any blank line, either at the top or start of your Blocklist, as you prefer. This leaves preview thumbnails intact, while stopping the ‘animated GIF-like’ previews that play when you mouseover the search result.

This or a similar rule should also work in other ad-blockers.