If you want the chart to not end instantly, on the main screen of the editor, click the song and go to Edit song data > Technical Data, then set End time to -1 or where you want the video to stop (it seems to have a long period with no notes at the end, so something like 99302 is probably more appropriate). It's currently set to 1, which is why it's ending instantly: the chart starts at 0ms and ends after 1ms.