Choosing a Video That Can Carry a Thread

Work through the tickbox list under the account's username rather than picking the first clip that comes to mind — a launch post, a strong opinion or an open question gives a thread somewhere real to sit, while a quiet upload with nothing to react to leaves supplied lines looking bolted on.
Check the entry chosen is still visible and unedited before paying, since a video pulled or switched to private afterwards leaves nothing for delivery to attach to. More than one entry can be ticked at once, so a launch clip and its follow-up can both gain a comments package together.

