you insert a drill bit into the tailstock and push the drill into a
rotating part that you are drilling.

Speaking of which...I finally ordered (and received) an Albrecht MT2
integral shank tailstock chuck for my SB 10L. Oh...it's nice. I already
have an R8 shank Albrecht for my mill. Now I'm wondering why I bought the
integral shank models? $400 invested, could have been $200 +change. I
guess I'll justify it by emphasizing the shorter setup times when I'm using
both machines.