That bolt holds the bell housing of the transmission onto the engine as well as the bracket for the transmission dipstick. It is a Torx E14 and is torqued to 28 ft lbs. You will need a 3/8 torque wrench, probably with a swivel to tighten.

After looking at the video it seems to be a transmission fluid leak. My guess would be the fluid is overflowing from the funnel (down by the spout and flowing over the lip of the steel tubing) down the tube until it meets that bolt and there it is easily seen. You have to add fluid very slowly as that is a small diameter dipstick tube. If you get a pool of fluid in the funnel it will leak out down by the spout before the fluid in the funnel all drains into the transmission. Another possibility would be that the dipstick tube has a crack in it near where it is welded to that bracket that the torx bolt secures to the engine.

What level of fluid does the dipstick indicate? After all you have lost I would thick it doesn't even show on the dipstick, but I could be wrong.