It would be nice to have a mean to enter a time position manually

Would be nice to have the current timestamp in the Timeline as a text input box to change it as desired or copy the current timestamp to the clipboard.

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In the meantime, you can do the following:

1) click on the time-line where you want the cursor to be, approximately; this will tell the cursor to move to wherever you clicked; the exact position of the cursor will be displayed on the left part of the time-line (the one that does not move), in the form of minutes, seconds, and image number (you will notice that seconds change roughly every 30 images, since there is approximately 30 images per second)

2) fine-tune the cursor position to where you want it exactly by using the arrow-left and arrow-right keys; one single hit on these keys moves the cursor by 1 image, which is the max precision you can get by nature of a video.