Stuart,
If it's any help I do this each fall so I can store the boat under the deck at the side of the house. It's all pretty much like the video only in reverse. According to me you still need help to pull the pin in the forestay while you stand on the tramp and then lower the mast. Put the pin back in the adjuster in the same place you took it out, probably top hole. Make sure you have the mast erection pin in the mast base before you start. Now here's the trick. When you have the mast down leave the pin in the base and, standing on the ground, hold the mast up at the top, by the Bob, and shake it fairly vigorously while you pull it apart. Sometimes I have to rest after a couple of tries. Sometimes I have to rest my shoulder against the Bob and push backwards while I shake it. Have faith, it will come out. I trailer mine with the mast apart and it hasn't gotten stuck yet.
As a thought: my boat started out in life as a "Classic" and so the bridle wires have clips on the end. This makes taking down and putting up the mast easier because the helper doesn't need any skill at all. Just snap on the clips and they're done. The Classic bridles are a little expensive but they are convenient. The only downside I can see is that a casual interfering type person or vandal could just unclip the wire and the mast would fall down. It hasn't happened to me yet. Leave me your email and I'll tell you if it does
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Take care.
Charles