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These are actions and functions that only have effect on the media object by which they are placed.
Behavior
Thumbnail aspect ratioratio 
The thumbnails are zoomed in to fill the square thumbnail area. This makes the objects easier to identify. This approach however hides some of the data on the edges. If you hover over the thumbnail, the whole object is displayed in its correct aspect ratio.
Thumbnail Preview 
In Premiere, the thumbnails are shown in the 16:9 aspect ratio. Bij hovering over the thumbnail you can get a quick overview of the contents of the video, without having to download it.
Hover icons for tooltip
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