paradiddle (PAR-uh-did-l) - n., in drumming, a steady 4-beat pattern of right-left-right-right and/or left-right-left-left.
Usually done slower than a roll. This, including variations, is a basic drum rudiment -- patterns you need to be able to bang out steadily as a core skill. The diddle part is the repeated right-right or left-left (origin unknown), and the para- seems to be humorously indicating the doubling -- or that's the standard theory.
Finally warmed up, he got the flam paradiddle-diddles going and began an accelerando.