Immediate debriefing is desirable. The observers' and testers' findings should be consolidated while the test is still fresh. After all testers have been observed, the facilitator may lead an additional work session with the observers to analyze and report the usability test findings. If a videotape was made, the observers might want to review portions of it. Time, cost, and videotape You'll need to decide if it's worth the extra effort and cost to videotape the test sessions.
Tapes can come in handy for comparing conflicting observations.
Also, seeing is believing. So if you anticipate needing to convince management, you'll definitely want to tape the test sessions. Put together a persuasive set of excerpts from the tape to back up your test findings. While a standard video camera will suffice, you can also rent or buy specialized usability testing equipment. If the usability testing equipment is installed in a permanent testing facility, observers may be able to work behind one-way mirrors so that the tester isn' t distracted by the feeling of being watched.