Timing

What things can I look at to fix a rough idle (see video with audio)? I made sure the breaker points were adjusted, is the next step valve clearances? If that doesn’t work, what’s next? 

Your question begs a multitude of answers.  What make, model and year is your bike and what else have you done to it besides adjust the points?  Others will no doubt chime in on your question, but a good start would be checking the valves for proper adjustment.  At the same time I would run a compression test and see what you have.  I would surmise you have at least cleaned and gapped the plugs?  What about timing?  Have you checked that?  Are you running all original components such as the air box, or do you have pod filters?  Depending on what bike you have there are other things that you can do such as carb adjustments etc.  Remember too that you simply must have a fully charged battery in your bike before you do anything to it.  Weak or discharged batteries will give you fits at times.  If you don't have a factory service manual I would suggest you obtain one and read through it at least a couple of times.  These manuals contain a lot of useful information when it comes to setting up your bike.  Realistically we need more information on your bike and what you have done to it so far.

Rick H.

Sorry, forgot to include important info. It’s a 1979 Kawasaki KZ750B. It has new plugs that have been gapped, it has a new battery that’s been charged, I installed a stock airbox with a new filter, I have a factory service manual that I’ve been looking through. I’m new to this as I’m sure you can tell, I still have to look into checking the timing.

Sounds like only one cylinder is firing. After it has been running a minute or two, spray a little mist of water on each exhaust pipe near the engine. If the water immediately sizzles and evaporates, that cylinder is firing. If the water is much slower to sizzle and evaporate on one pipe, you will have identified the problem child.
Pull the spark plug from the non-firing cylinder and reinsert it into the spark plug cap in a way that allows the spark plug threads to have good contact with the engine, preferably away from the spark plug hole. Try to start the engine and look for a spark. It should be blue or bluish white. If there is no spark, or it is yellow and weak, the problem will likely be in the secondary side of the ignition. If there is healthy spark, the problem is elsewhere.
If the bike has been sitting unridden for a while, the pilot circuit in each carburetor is likely clogged with dried fuel.
If the carb holders are old, hard and cracked, they may be leaking enough to cause a misfire.
If the carbs have recently been removed and reinstalled, they may not be fully seated in the holders.

Rick’s advice about the routine maintenance is good, especially on an old machine that is new to you. Valve adjustment is often neglected and can cause a variety of problems if ignored too long. Performing all the routine maintenance will eliminate potential problems, help familiarize you with the machine, and will help the bike run its best.