canuck - 6:19 pm on Nov 25, 2010 (gmt 0)
YouTube videos are free to upload, and can be up to 15 minutes in length (as of July/10).
I've used YouTube on a commercial site over the last year, and with YouTube's "embed" code users don't have to leave the website to watch the videos. I've had good success using YouTube but having that "YouTube" logo in the lower-right corner may not be professional enough for some industries. (I'm in the Tech field, so YouTube is fine.)
Also, unlike watching videos on YouTube, when you embed them on your website there's no pesky 'Just watched' and 'Up next' video suggestions to guide users away at the end of the video - only a 'Replay' button.