On the DVD that accompanies Beyond Basic Percussion, some DVD players may loop infinitely during the Triangle portion of the Technique Demonstration videos. The issue seems to exist whether you select just those videos from the menu, or if you happen upon them in sequence from an earlier point in the sequence.
The workaround for this issue is simply to either bypass those videos, or press "Menu" on your DVD remote to return to the main Technique Demonstration screen. From there, you can select any of the videos that occur after the Triangle ones in the sequence.
The problem exists in the scripting of the DVD, and has since been fixed so as to not show up in subsequent pressings of the disc. We apologize for any inconvenience this causes.