Yes you can leave the hot spring but don't expect it the timer to be at 1:00:00 if you intend to leave after 1 hour. I don't know how they round it but the system rounds it to certain time so it could be 1:03:00, 1:04:00, etc. Point is that It shouldn't add no more than 5 mins onto the timer. That's why the video you saw went back to 2:00:00 since the guy left to early (like 5mins) since he left between 1:55:00-2:00:00 and it resets back to the closet minute. Just make sure you stay in the hot spring and complete the timer during the day before reset.