First. Maybe get a moderate to move this to slant six. This forum is for high performance modifications and wont get as many looks from people who might be able to help you out.
Second. its really helpful to include the year, model, transmission, and accessories (like air conditioning). I can spot a bunch in your video but thats all time consuming and still if I get it wrong will be working on the wrong assumptions.
I'm guessing this is a '72 California equipped engine with A/C.
Basic of hoses;
There are a few critical few systems that use vacuum hose. Identify them by what they are for.
Positive Crank Ventilation (PCV) This replaced the draft tube. There will be one large line from the PCV valve to a manifold vacuum source. There will be a second hose for make up air from the air cleaner to the valve cover.
Vacuum advance on the distributor. This provides additional lead time for the spark at low and moderate throttle while driving. The vacuum comes from the 'timed port' on the carburetor. From the video it looks like your car has a California NOx reduction setup that I'm not particularly familiar with. I know the later OSAC version made the cars less drivable (delayed engine response to throttle input).
From page 25-7 of the Plymouth Chassis Manual.
you can download the whole manual from
www.mymopar.com
For the system to work, the electrical thermal and speed switches will need to work as well. I don't know what the situation is with CARB. If it the system is not all working, connect that vac hose from the distributor directly to the carburator's timing vacuum port. That way you'll get the benefit of the improved fuel milage that comes with using vacuum advance.
You can also read explanations about the various emissions reduction systems in the Master Technicians Service Conference available from the same website.
Air Cleaner has one or two vacuum operated flaps. There may be one in the nozzle that must open when the engine starts. It closes when the engine is off to prevent fuel vapor from escaping. It probably also has a flap that opens to let in warm air heated from the manifold as needed for a more constant air temperature and speed warm up.
Vapor collection. Your car may have a fuel vapor collection cannister. Some of these are not vac lines but bring fuel vapor to the charcoal. The lines are or were color coded.
The A/C may have a vacuum line for actuating some control.
A brake power booster will have a large vacuum line to a manifold vacuum port.
