The daily Orion webcast has gotten better and better as the weeks have gone by. It's been great to see improvements in the format, sound, content and a dozen little things.
One of the remaining problems has been inconsistency in how the shots have been framed. Fortunately, iMovie makes it really easy to adjust the framing.
In the toolbar, just below the player window, you'll see the cropping tool (it looks like a rectangle with little tails in two of its corners). Select the clip from the timeline that you'd like to tighten up, then click the cropping tool and adjust the rectangle in the player window. Here's a short clip I adjusted using the tool: