Really liked your video. I have been doing almost the same technique on my freight cars. A note on the "sponges" that come with the set. I found they are only good on a smooth flat finish. Going across grills, rivets, etc. tears them up quickly. Getting ready to do my first loco. A Bachmann Sound Value RS-3 decorated for the Seaboard Air Line. Found some great reference photos online to go by.
If possible, make sure that the lights over your workbench are the same lights you have over your layout. It can make a big difference in the amount of weathering you apply
Important to note, when using an airbrush for spraying acrylic paint, brushed on oils, or weathering powders. They dry slowly and can be removed if you mess up. Rule of thumb, clear coat every layer, so if your next layer isnt right, just remove it with either water or alcohol. Its not hard at all.