The quick preview of an item can be accessed if that item has a preview associated with it by right clicking on it and selecting quick view or preview.  Doing so will pop up a larger window showing the large [preview] of that item.  Click again once to close that image.  You can also right click to download a copy of the low resolution preview. 
You can also have a quick view of the given item if it has a thumbnail generated by simply moving the file above it.