https://connect.mozilla.org/t5/discussions/weird-youtube-behavior-on-currently-playing/m-p/109855#M42274 <P>MacBook Pro 14" (M3 Max, 2023) - Firefox 145.00</P><P>When playing a YouTube video, moving the mouse cursor to a video thumbnail causes the currently-playing video to visibly darken while the mouse pointer is hovering over a video thumbnail.</P><P>Behavior does not replicate on Safari Version 26.1 (21622.2.11.11.9) or Vivaldi&nbsp;7.6.3797.63 (Stable channel) (arm64).&nbsp;</P><P>The only currently-running extensions are uBlock Origin and Bitwarden.&nbsp;</P> Wed, 12 Nov 2025 16:42:38 GMT SporkWriter84 2025-11-12T16:42:38Z https://connect.mozilla.org/t5/discussions/weird-youtube-behavior-on-currently-playing/m-p/109855#M42274 <P>MacBook Pro 14" (M3 Max, 2023) - Firefox 145.00</P><P>When playing a YouTube video, moving the mouse cursor to a video thumbnail causes the currently-playing video to visibly darken while the mouse pointer is hovering over a video thumbnail.</P><P>Behavior does not replicate on Safari Version 26.1 (21622.2.11.11.9) or Vivaldi&nbsp;7.6.3797.63 (Stable channel) (arm64).&nbsp;</P><P>The only currently-running extensions are uBlock Origin and Bitwarden.&nbsp;</P> Wed, 12 Nov 2025 16:42:38 GMT https://connect.mozilla.org/t5/discussions/weird-youtube-behavior-on-currently-playing/m-p/109855#M42274 SporkWriter84 2025-11-12T16:42:38Z