Oh, it has nothing to do with commerce - you don't strike us as that type, although they are one we're wary for as you'll understand.
It's about our hobby, and the dangers we know exist. We know people who have been robbed. We have members who know people who have been killed for their coins. So, in a general sense we strongly discourage collectors posting information about their collections - or their collecting activities - online in any social-media-exposed situation. And with YouTube's integration into Google and Facebook, it starts resembling a one-stop shopping experience for those looking to gather your personal information. Most would be surprised at how much information we leave laying around online about ourselves, little nuggets waiting to be collated into a bigger picture. If you're within reach of the (intelligent) miscreant doing it, you win a visit.
This all is as much for those reading but not posting as it is for you. Readers usually outnumber posters 10:1 and we know we're speaking to an audience.