For the record, it is not blue tape he is using, but a double-sided adhesive tape (adhesive on both sides) as used for sticking name-plates permanently to walls etc. Just google it and be astounded

The surface is 3M's 9448A Double Coated Tissue Tape which is a nearly rigid 0.01" thick plastic with an adhesive backing to hold it to the heated aluminum plate bed. It is considered a consumable and has to be replaced when it becomes damaged.