Favor close ups. Use online long shots to establish a location, but keep the shot lengths shorter, because they are only there to provide orientation. For an online long shot, dominate the frame with a telling, readily recognized detail, like a single dominant pine tree in the snow to show that it's Christmas. Unlike contemporary television where the medium shot dominates, close ups are your bread and butter shots. If like Bill Murray or Edward James Olmos, you still bear the scars of teenage acne, online video's low resolution can actually make you letter better than TV.
Know that high compression does not like fast movement or rapid color changes. It's easier on the eye to keep your shots stable, ideally on a tripod if possible. Keep your transitions simple. Remember that in the early days of movie making thousands of hours of stories were told with transitions no more complicated than cuts or dissolves. The page turns, fancy wipes and 3-D DVE transitions that all amazed us back when Ampex came out with its ADO simply don't look good online. The edges are pixilated, jagged and distracting.
Try to use a 4:2:2 format like DV-50 or Digital Betacam. DV is fine for the Internet but whether or not you'll ultimately encode in Flash, QuickTime or Windows Media, you'll only hurt yourself by compressing an already highly compressed format. Shoot in the highest possible digital quality that you can afford.
Make sure your audio is clear and understandable. In contrast to video, audio is not noticeably compressed online. Since your viewer will already be working hard to perceive the video, make the sounds easy to grasp.
Keep your show duration short. Online videos watching is frequently a stolen moment. If the content is particularly compelling, you can go as long as seven or eight minutes. For the most part, keep your stories under three. On a subconscious level when you watch online video, you still don't give it the respect that you give to television.