Pinioned birds usually only have one wing clipped. The primary feathers are the ones being clipped (the fingers on the wing). Is it visible? Yes, a bit. On a standing mount it is less visible, and usually the mount has the pinioned wing facing away from the viewer or at the wall. When a duck is in a sitting position, there really isn't much wing showing. Just a bit of the speculum, and the tips of the wings that lay near the tail. The leading edge is almost completely hidden.
I wasn't trained using videos, so I really don't have any first hand knowledge, but a few key names to look for are Dave Luke, Stephen Savides, Frank Newmeyer, and Corey Caruthers to name a few. If you go to taxidermy.net, you will find a beginners section that can help you find videos, and even answer a few questions. There is also a bird section, but too many elitests in there right now for a beginner :laughing: . Use the search button first, then ask your question, and of course feel free to ask ANY question here, and I'd be glad to help to the best of my ability. If you think your question is too dumb, then send me (or any of the other Moderators) a PM, and we'll try and answer. If you post on here, it may be a question that another newbie would like to ask, but doesn't want to put himself out there, and it may just help someone else.