Do you have the missing parts, or are the pics all that you have? The fitting missing from the fuel tank has a dip tube on it. You won't be able to draw fuel from the tank without one. That fitting will connect to a hose that then goes to one fuel pump. Another hose comes out of that fuel pump into another fuel pump. Another hose comes from that pump to the first canister, a water separator. Then to the next can (a filter), then the next can (another filter), then to a check valve, then to your injector pump. Another hose will come from the injection pump back to the fuel tank.
The aux fitting on the fuel tank will go to an aux pump (comes from it, actually). Don't bother with it unless you need it.
If there's crud in the tank, you can take the hose that would go to the first pump I mentioned, and drop it in your gas can (make sure you mark that can as diesel; unless it's actually gasoline, which will probably damage the machine).
There also needs to be a wire/plug connected to the electrical fitting on the tank. Look for it hanging in that vicinity.
Don't use dirty fuel and don't bypass the filters, you can cause yourself a world of misery if you push rust flakes or something into the injection pump. Check the tank carefully, and you should avoid using it if it has water or significant rust in it. It also has a drain, make sure that's closed before adding any fuel. If you use the tank, pour in just a little fuel, and then look for signs of leaks.
Are you sure you saw that exact genset running in the vid? Are you sure the vid was 3 months ago?
You could have several problems. The TM's may not cover missing pieces, so you should look very closely yourself for signs of things missing where it looks like something once was. Post pics, and guys on here can help you figure a lot out. I've learned quite a bit on here and another site since I started getting active. Makes me regret all the units I sold without bothering to glance through.