Here are some sample presentations of various quality (both in the content and media) that you can use to compare/contrast your performance with. Pay special attention to the organization of their presentations and the approaches that they take with their audience, their body language (when video of the speaker is available), and their spoken language.

SciVee TV – This is the coolest site that I’ve found so far. It’s a video sharing site for scientific presentations. I think that you’ll be impressed with the offerings.

Dr. Kronenberg research presentation – Actions of the PTH/PTHrP Receptor in Bone – Sept. 19, 2006 (video w/PPT — 60 min)

Dr. Kronenberg research presentation – The Perichondrium in Bone Development – April 25-28, 2007 (audio w/PPT — 30 min)

Rice University Webcasts – there are a great variety of topics associated with this site, with a good number being in the sciences. However, these are mostly in seminar formats around an hour in length.

MedicalRounds lots of great presentations in audio/ppt format. These are mostly longer presentations (around 1 hr). They mostly focus on medical clinicians, but could be for researchers as well.