Watched the video. They seem to go back to the 2 cent stamp, a lot. However, isn't using TP, PP, etc, enough, so that we don't need to use stamps? That's what the 742.1 and 742.2 would indicate.
Do I need to have a red thumb print for where the stamp would be, or would I just use Tax Percue/Porte Pay/Postage Prepaid? The video indicated that UPU was more for if one is based outside the US, with one being in the US to use the 742.1 and 742.2. Or is this flexible?