The B stands for Back fist, the T is a thrust punch and the C is a cross hand shuto. This is a classic “Kempo” style striking combination. Have fun with this one!
BTC again stands for Backfist, Thrust, Cross Shuto. You can see how the range works on each of the strikes and the importance of working your control with a partner.
Self Control is critical when working with a partner. The goal is to be able to do this, as they demonstrate, at a fast pace and striking right next to the target without making contact.