The knot you tied in your video is a overhand Knot on a bight not a overhand follow through.
The overhand follow through, ring bend, or water knot doesn’t enter the the same side as the loop end but the same end as the source end. This is when you are using it to make a loop and therefore one piece of webbing on itself.
The water knot often used to attach two pieces of webbing together looks very similar dues it having two pieces of webbing however they are different in how they are tied, where the stress is in the knot, and how much they slip. For bridges I use a water knot or ring bend.
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Overhand knots on a bite are know to slip through the knot when experiencing fall loads so it’s good you’re backing them up with at least something.
With either of these knots you want to leave sufficient tag end or tie a stopper knot to mitigate a pull through.