Good. I should have included asking if your brake lights work properly with and without the emergency flashers on. Applying the brake should override the rear flashing lights.
It's a process of elimination. If your lights work properly under that specific state that tells me a couple things -
1. Your lights have an adequate ground because the brake, turn signal & flasher all use the same bulb element and wiring.
2. Your turn signal switch, at rest only, is OK.
3. Your emergency flasher is good.
Now, there are two issues to deal with. There may be some commonality but the responsibility of the steering column /mechanism harness to honk the horns is to deliver a ground potential to the horn relay via the black/tracer wire from the column. But, when it comes to the lights, the turn signal mechanism switches (+) positive potentials only.
I've looked at the video many time but I just cannot see it clearly enough. There are some things to keep in mind. First, the emergency flasher is a different circuit and feeds the turn signal mechanism on a different lead than the turn signal flasher. The turn signal mechanism's responsibility is to actuate the turn signal flasher and to route that signal to the appropriate rear lamp while maintaining the brake signal integrity to the opposing rear lamp and flash only signal to the front lamps. That's a lot but you have neither left or right signals which have different contact positions within the turn signal mechanism. The common point is the toward the turn signal flasher.
That's not saying your old turn signal mechanism is good by any means but it is important to understand that the mechanism/harness have different jobs, some easy like the horn (-) and some complicated like switching certain signals to some bulbs while maintaining other signals to the rest (+).
