If Mac... there is only one true genius in this realm, iShowuHD Pro.
Had this discussion myself a while ago, and Kier uses the standard Mac screen capture I believe, then uploads it direct to Vimeo. I use iShowU HD Pro in 1080p, then upload to my Vimeo Plus account.
Having a Vimeo plus account makes a huge difference to your video quality. You can screen capture in 1080p, upload to Vimeo and present it in true 1080p. Youtube doesn't play nice with 1080p unless you have a special account that will do it correctly. Even Vimeo, when you upload 1080p, having a plus account allows you to convert and display 1080p correctly. Youtube will screw it up on a standard account.
I concur. Especially comparing Kier's Vimeo screen capture videos vs the how to' videos I am making and uploading to my smugmug account - which costs the same as Vimeo. Ironically with normal everyday videos that do not have anything to do with computers Smugmug works 'ok'.
And I am sure there are many other places to upload, or even host the videos on your own server.
Quick tip: Clear audio can add a tremendous amount of value to a how to video..