Core has both Simple and Advanced Players which are selected using the tabs above the video preview window (see below).

See other sections including: What is a bin clip and how do I create one? and What controls and configurations does the advanced player have?

The Simple Player (Adobe Flash) is ideal for basic previewing and non-frame accurate clip creation.

The Advanced Player (HTML5) has enhanced features and controls for tasks such as frame accurate clip creation. Hover-over all player controls with your mouse to display their descriptions.